ALSA: improve buffer size computations for USB PCM audio

This patch changes the way URBs are allocated and their sizes are determined for PCM playback in the snd-usb-audio driver. Currently the driver allocates too few URBs for endpoints that don't use implicit sync, making underruns more likely to occur. This may be a holdover from before I/O delays could be measured accurately; in any case, it is no longer necessary. The patch allocates as many URBs as possible, subject to four limitations: The total number of URBs for the endpoint is not allowed to exceed MAX_URBS (which the patch increases from 8 to 12). The total number of packets per URB is not allowed to exceed MAX_PACKS (or MAX_PACKS_HS for high-speed devices), which is decreased from 20 to 6. The total duration of queued data is not allowed to exceed MAX_QUEUE, which is decreased from 24 ms to 18 ms. The total number of ALSA frames in the output queue is not allowed to exceed the ALSA buffer size. The last requirement is the hardest to implement. Currently the number of URBs needed to fill a buffer cannot be determined in advance, because a buffer contains a fixed number of frames whereas the number of frames in an URB varies to match shifts in the device's clock rate. To solve this problem, the patch changes the logic for deciding how many packets an URB should contain. Rather than using as many as possible without exceeding an ALSA period boundary, now the driver uses only as many packets as needed to transfer a predetermined number of frames. As a result, unless the device's clock has an exceedingly variable rate, the number of URBs making up each period (and hence each buffer) will remain constant. The overall effect of the patch is that playback works better in low-latency settings. The user can still specify values for frames/period and periods/buffer that exceed the capabilities of the hardware, of course. But for values that are within those capabilities, the performance will be improved. For example, testing shows that a high-speed device can handle 32 frames/period and 3 periods/buffer at 48 KHz, whereas the current driver starts to get glitchy at 64 frames/period and 2 periods/buffer. A side effect of these changes is that the "nrpacks" module parameter is no longer used. The patch removes it. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: Clemens Ladisch <clemens@ladisch.de> Tested-by: Daniel Mack <zonque@gmail.com> Tested-by: Eldad Zack <eldad@fogrefinery.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
author: Alan Stern <stern@rowland.harvard.edu> 2013-09-24 15:51:58 -0400
committer: Takashi Iwai <tiwai@suse.de> 2013-09-26 04:25:31 -0400
commit: 976b6c064a957445eb0573b270f2d0282630e9b9 (patch)
tree: 3a80a94273feeb9c30ac6f2e23976d020dc44aaf /sound/usb
parent: e8bc99425e8159cd5f56bb76419158857bd358ed (diff)
6 files changed, 82 insertions, 59 deletions
diff --git a/sound/usb/card.c b/sound/usb/card.c
index 64952e2d3ed1..d1f54dfe41d5 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -79,7 +79,6 @@ static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;/* Enable this card *
 /* Vendor/product IDs for this card */
 static int vid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
 static int pid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
-static int nrpacks = 8;         /* max. number of packets per urb */
 static int device_setup[SNDRV_CARDS]; /* device parameter for this card */
 static bool ignore_ctl_error;
 static bool autoclock = true;
@@ -94,8 +93,6 @@ module_param_array(vid, int, NULL, 0444);
 MODULE_PARM_DESC(vid, "Vendor ID for the USB audio device.");
 module_param_array(pid, int, NULL, 0444);
 MODULE_PARM_DESC(pid, "Product ID for the USB audio device.");
-module_param(nrpacks, int, 0644);
-MODULE_PARM_DESC(nrpacks, "Max. number of packets per URB.");
 module_param_array(device_setup, int, NULL, 0444);
 MODULE_PARM_DESC(device_setup, "Specific device setup (if needed).");
 module_param(ignore_ctl_error, bool, 0444);
@@ -374,7 +371,6 @@ static int snd_usb_audio_create(struct usb_device *dev, int idx,
        chip->dev = dev;
        chip->card = card;
        chip->setup = device_setup[idx];
-        chip->nrpacks = nrpacks;
        chip->autoclock = autoclock;
        chip->probing = 1;
@@ -756,10 +752,6 @@ static struct usb_driver usb_audio_driver = {
 static int __init snd_usb_audio_init(void)
 {
-        if (nrpacks < 1 || nrpacks > MAX_PACKS) {
-                printk(KERN_WARNING "invalid nrpacks value.\n");
-                return -EINVAL;
-        }
        return usb_register(&usb_audio_driver);
 }
diff --git a/sound/usb/card.h b/sound/usb/card.h
index 5ecacaa90b53..ca98a9b915c9 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -2,11 +2,11 @@
 #define __USBAUDIO_CARD_H
 #define MAX_NR_RATES    1024
-#define MAX_PACKS       20
+#define MAX_PACKS       6               /* per URB */
 #define MAX_PACKS_HS    (MAX_PACKS * 8) /* in high speed mode */
-#define MAX_URBS        8
+#define MAX_URBS        12
 #define SYNC_URBS       4       /* always four urbs for sync */
-#define MAX_QUEUE       24      /* try not to exceed this queue length, in ms */
+#define MAX_QUEUE       18      /* try not to exceed this queue length, in ms */
 struct audioformat {
        struct list_head list;
@@ -87,6 +87,7 @@ struct snd_usb_endpoint {
        unsigned int phase;             /* phase accumulator */
        unsigned int maxpacksize;       /* max packet size in bytes */
        unsigned int maxframesize;      /* max packet size in frames */
+        unsigned int max_urb_frames;    /* max URB size in frames */
        unsigned int curpacksize;       /* current packet size in bytes (for capture) */
        unsigned int curframesize;      /* current packet size in frames (for capture) */
        unsigned int syncmaxsize;       /* sync endpoint packet size */
@@ -116,6 +117,8 @@ struct snd_usb_substream {
        unsigned int channels_max;      /* max channels in the all audiofmts */
        unsigned int cur_rate;          /* current rate (for hw_params callback) */
        unsigned int period_bytes;      /* current period bytes (for hw_params callback) */
+        unsigned int period_frames;     /* current frames per period */
+        unsigned int buffer_periods;    /* current periods per buffer */
        unsigned int altset_idx;     /* USB data format: index of alternate setting */
        unsigned int txfr_quirk:1;      /* allow sub-frame alignment */
        unsigned int fmt_type;          /* USB audio format type (1-3) */
@@ -125,6 +128,7 @@ struct snd_usb_substream {
        unsigned int hwptr_done;        /* processed byte position in the buffer */
        unsigned int transfer_done;             /* processed frames since last period update */
+        unsigned int frame_limit;       /* limits number of packets in URB */
        /* data and sync endpoints for this stream */
        unsigned int ep_num;            /* the endpoint number */
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 93e970f2b3c0..21dc6422d747 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -574,11 +574,14 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep,
                              snd_pcm_format_t pcm_format,
                              unsigned int channels,
                              unsigned int period_bytes,
+                              unsigned int frames_per_period,
+                              unsigned int periods_per_buffer,
                              struct audioformat *fmt,
                              struct snd_usb_endpoint *sync_ep)
 {
-        unsigned int maxsize, i, urb_packs, total_packs, packs_per_ms;
+        unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
-        int is_playback = usb_pipeout(ep->pipe);
+        unsigned int max_packs_per_period, urbs_per_period, urb_packs;
+        unsigned int max_urbs, i;
        int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
        if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
@@ -611,58 +614,67 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep,
        else
                ep->curpacksize = maxsize;
-        if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL)
+        if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
                packs_per_ms = 8 >> ep->datainterval;
-        else
+                max_packs_per_urb = MAX_PACKS_HS;
-                packs_per_ms = 1;
-        if (is_playback && !snd_usb_endpoint_implicit_feedback_sink(ep)) {
-                urb_packs = max(ep->chip->nrpacks, 1);
-                urb_packs = min(urb_packs, (unsigned int) MAX_PACKS);
        } else {
-                urb_packs = 1;
+                packs_per_ms = 1;
+                max_packs_per_urb = MAX_PACKS;
        }
+        if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
+                max_packs_per_urb = min(max_packs_per_urb,
+                                        1U << sync_ep->syncinterval);
+        max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
-        urb_packs *= packs_per_ms;
+        /*
+         * Capture endpoints need to use small URBs because there's no way
+         * to tell in advance where the next period will end, and we don't
+         * want the next URB to complete much after the period ends.
+         *
+         * Playback endpoints with implicit sync much use the same parameters
+         * as their corresponding capture endpoint.
+         */
+        if (usb_pipein(ep->pipe) ||
+                        snd_usb_endpoint_implicit_feedback_sink(ep)) {
-        if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
+                /* make capture URBs <= 1 ms and smaller than a period */
-                urb_packs = min(urb_packs, 1U << sync_ep->syncinterval);
+                urb_packs = min(max_packs_per_urb, packs_per_ms);
+                while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
+                        urb_packs >>= 1;
+                ep->nurbs = MAX_URBS;
-        /* decide how many packets to be used */
+        /*
-        if (is_playback && !snd_usb_endpoint_implicit_feedback_sink(ep)) {
+         * Playback endpoints without implicit sync are adjusted so that
-                unsigned int minsize, maxpacks;
+         * a period fits as evenly as possible in the smallest number of
+         * URBs.  The total number of URBs is adjusted to the size of the
+         * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
+         */
+        } else {
                /* determine how small a packet can be */
-                minsize = (ep->freqn >> (16 - ep->datainterval))
+                minsize = (ep->freqn >> (16 - ep->datainterval)) *
-                          * (frame_bits >> 3);
+                                (frame_bits >> 3);
                /* with sync from device, assume it can be 12% lower */
                if (sync_ep)
                        minsize -= minsize >> 3;
                minsize = max(minsize, 1u);
-                total_packs = (period_bytes + minsize - 1) / minsize;
-                /* we need at least two URBs for queueing */
-                if (total_packs < 2) {
-                        total_packs = 2;
-                } else {
-                        /* and we don't want too long a queue either */
-                        maxpacks = max(MAX_QUEUE * packs_per_ms, urb_packs * 2);
-                        total_packs = min(total_packs, maxpacks);
-                }
-        } else {
-                while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
-                        urb_packs >>= 1;
-                total_packs = MAX_URBS * urb_packs;
-        }
-        ep->nurbs = (total_packs + urb_packs - 1) / urb_packs;
+                /* how many packets will contain an entire ALSA period? */
-        if (ep->nurbs > MAX_URBS) {
+                max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);
-                /* too much... */
-                ep->nurbs = MAX_URBS;
+                /* how many URBs will contain a period? */
-                total_packs = MAX_URBS * urb_packs;
+                urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
-        } else if (ep->nurbs < 2) {
+                                max_packs_per_urb);
-                /* too little - we need at least two packets
+                /* how many packets are needed in each URB? */
-                 * to ensure contiguous playback/capture
+                urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
-                 */
-                ep->nurbs = 2;
+                /* limit the number of frames in a single URB */
+                ep->max_urb_frames = DIV_ROUND_UP(frames_per_period,
+                                        urbs_per_period);
+                /* try to use enough URBs to contain an entire ALSA buffer */
+                max_urbs = min((unsigned) MAX_URBS,
+                                MAX_QUEUE * packs_per_ms / urb_packs);
+                ep->nurbs = min(max_urbs, urbs_per_period * periods_per_buffer);
        }
        /* allocate and initialize data urbs */
@@ -670,8 +682,7 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep,
                struct snd_urb_ctx *u = &ep->urb[i];
                u->index = i;
                u->ep = ep;
-                u->packets = (i + 1) * total_packs / ep->nurbs
+                u->packets = urb_packs;
-                        - i * total_packs / ep->nurbs;
                u->buffer_size = maxsize * u->packets;
                if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
@@ -748,6 +759,8 @@ out_of_memory:
 * @pcm_format: the audio fomat.
 * @channels: the number of audio channels.
 * @period_bytes: the number of bytes in one alsa period.
+ * @period_frames: the number of frames in one alsa period.
+ * @buffer_periods: the number of periods in one alsa buffer.
 * @rate: the frame rate.
 * @fmt: the USB audio format information
 * @sync_ep: the sync endpoint to use, if any
@@ -760,6 +773,8 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
                                snd_pcm_format_t pcm_format,
                                unsigned int channels,
                                unsigned int period_bytes,
+                                unsigned int period_frames,
+                                unsigned int buffer_periods,
                                unsigned int rate,
                                struct audioformat *fmt,
                                struct snd_usb_endpoint *sync_ep)
@@ -793,7 +808,8 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
        switch (ep->type) {
        case  SND_USB_ENDPOINT_TYPE_DATA:
                err = data_ep_set_params(ep, pcm_format, channels,
-                                         period_bytes, fmt, sync_ep);
+                                         period_bytes, period_frames,
+                                         buffer_periods, fmt, sync_ep);
                break;
        case  SND_USB_ENDPOINT_TYPE_SYNC:
                err = sync_ep_set_params(ep, fmt);
diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h
index 2287adf5ca59..3bd02f0d226c 100644
--- a/sound/usb/endpoint.h
+++ b/sound/usb/endpoint.h
@@ -12,6 +12,8 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
                                snd_pcm_format_t pcm_format,
                                unsigned int channels,
                                unsigned int period_bytes,
+                                unsigned int period_frames,
+                                unsigned int buffer_periods,
                                unsigned int rate,
                                struct audioformat *fmt,
                                struct snd_usb_endpoint *sync_ep);
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index b375d58871e7..19e79953f2e3 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -595,6 +595,7 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs)
                                                   subs->pcm_format,
                                                   subs->channels,
                                                   subs->period_bytes,
+                                                   0, 0,
                                                   subs->cur_rate,
                                                   subs->cur_audiofmt,
                                                   NULL);
@@ -631,6 +632,7 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs)
                                          subs->pcm_format,
                                          sync_fp->channels,
                                          sync_period_bytes,
+                                          0, 0,
                                          subs->cur_rate,
                                          sync_fp,
                                          NULL);
@@ -653,6 +655,8 @@ static int configure_endpoint(struct snd_usb_substream *subs)
                                          subs->pcm_format,
                                          subs->channels,
                                          subs->period_bytes,
+                                          subs->period_frames,
+                                          subs->buffer_periods,
                                          subs->cur_rate,
                                          subs->cur_audiofmt,
                                          subs->sync_endpoint);
@@ -689,6 +693,8 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
        subs->pcm_format = params_format(hw_params);
        subs->period_bytes = params_period_bytes(hw_params);
+        subs->period_frames = params_period_size(hw_params);
+        subs->buffer_periods = params_periods(hw_params);
        subs->channels = params_channels(hw_params);
        subs->cur_rate = params_rate(hw_params);
@@ -1363,6 +1369,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
        frames = 0;
        urb->number_of_packets = 0;
        spin_lock_irqsave(&subs->lock, flags);
+        subs->frame_limit += ep->max_urb_frames;
        for (i = 0; i < ctx->packets; i++) {
                if (ctx->packet_size[i])
                        counts = ctx->packet_size[i];
@@ -1377,6 +1384,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
                subs->transfer_done += counts;
                if (subs->transfer_done >= runtime->period_size) {
                        subs->transfer_done -= runtime->period_size;
+                        subs->frame_limit = 0;
                        period_elapsed = 1;
                        if (subs->fmt_type == UAC_FORMAT_TYPE_II) {
                                if (subs->transfer_done > 0) {
@@ -1399,8 +1407,10 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
                                break;
                        }
                }
-                if (period_elapsed &&
+                /* finish at the period boundary or after enough frames */
-                    !snd_usb_endpoint_implicit_feedback_sink(subs->data_endpoint)) /* finish at the period boundary */
+                if ((period_elapsed ||
+                                subs->transfer_done >= subs->frame_limit) &&
+                    !snd_usb_endpoint_implicit_feedback_sink(ep))
                        break;
        }
        bytes = frames * ep->stride;
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index caabe9b3af49..5d2fe0530745 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -55,7 +55,6 @@ struct snd_usb_audio {
        struct list_head mixer_list;    /* list of mixer interfaces */
        int setup;                      /* from the 'device_setup' module param */
-        int nrpacks;                    /* from the 'nrpacks' module param */
        bool autoclock;                 /* from the 'autoclock' module param */
        struct usb_host_interface *ctrl_intf;   /* the audio control interface */
author	Alan Stern <stern@rowland.harvard.edu>	2013-09-24 15:51:58 -0400
committer	Takashi Iwai <tiwai@suse.de>	2013-09-26 04:25:31 -0400
commit	976b6c064a957445eb0573b270f2d0282630e9b9 (patch)
tree	3a80a94273feeb9c30ac6f2e23976d020dc44aaf /sound/usb
parent	e8bc99425e8159cd5f56bb76419158857bd358ed (diff)

diff --git a/sound/usb/card.c b/sound/usb/card.c index 64952e2d3ed1..d1f54dfe41d5 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c
@@ -79,7 +79,6 @@ static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;/* Enable this card *
79	/* Vendor/product IDs for this card */	79	/* Vendor/product IDs for this card */
80	static int vid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };	80	static int vid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
81	static int pid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };	81	static int pid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
82	static int nrpacks = 8; /* max. number of packets per urb */
83	static int device_setup[SNDRV_CARDS]; /* device parameter for this card */	82	static int device_setup[SNDRV_CARDS]; /* device parameter for this card */
84	static bool ignore_ctl_error;	83	static bool ignore_ctl_error;
85	static bool autoclock = true;	84	static bool autoclock = true;
@@ -94,8 +93,6 @@ module_param_array(vid, int, NULL, 0444);
94	MODULE_PARM_DESC(vid, "Vendor ID for the USB audio device.");	93	MODULE_PARM_DESC(vid, "Vendor ID for the USB audio device.");
95	module_param_array(pid, int, NULL, 0444);	94	module_param_array(pid, int, NULL, 0444);
96	MODULE_PARM_DESC(pid, "Product ID for the USB audio device.");	95	MODULE_PARM_DESC(pid, "Product ID for the USB audio device.");
97	module_param(nrpacks, int, 0644);
98	MODULE_PARM_DESC(nrpacks, "Max. number of packets per URB.");
99	module_param_array(device_setup, int, NULL, 0444);	96	module_param_array(device_setup, int, NULL, 0444);
100	MODULE_PARM_DESC(device_setup, "Specific device setup (if needed).");	97	MODULE_PARM_DESC(device_setup, "Specific device setup (if needed).");
101	module_param(ignore_ctl_error, bool, 0444);	98	module_param(ignore_ctl_error, bool, 0444);
@@ -374,7 +371,6 @@ static int snd_usb_audio_create(struct usb_device *dev, int idx,
374	chip->dev = dev;	371	chip->dev = dev;
375	chip->card = card;	372	chip->card = card;
376	chip->setup = device_setup[idx];	373	chip->setup = device_setup[idx];
377	chip->nrpacks = nrpacks;
378	chip->autoclock = autoclock;	374	chip->autoclock = autoclock;
379	chip->probing = 1;	375	chip->probing = 1;
380		376
@@ -756,10 +752,6 @@ static struct usb_driver usb_audio_driver = {
756		752
757	static int __init snd_usb_audio_init(void)	753	static int __init snd_usb_audio_init(void)
758	{	754	{
759	if (nrpacks < 1 \|\| nrpacks > MAX_PACKS) {
760	printk(KERN_WARNING "invalid nrpacks value.\n");
761	return -EINVAL;
762	}
763	return usb_register(&usb_audio_driver);	755	return usb_register(&usb_audio_driver);
764	}	756	}
765		757


diff --git a/sound/usb/card.h b/sound/usb/card.h index 5ecacaa90b53..ca98a9b915c9 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h
@@ -2,11 +2,11 @@
2	#define __USBAUDIO_CARD_H	2	#define __USBAUDIO_CARD_H
3		3
4	#define MAX_NR_RATES 1024	4	#define MAX_NR_RATES 1024
5	#define MAX_PACKS 20	5	#define MAX_PACKS 6 /* per URB */
6	#define MAX_PACKS_HS (MAX_PACKS * 8) /* in high speed mode */	6	#define MAX_PACKS_HS (MAX_PACKS * 8) /* in high speed mode */
7	#define MAX_URBS 8	7	#define MAX_URBS 12
8	#define SYNC_URBS 4 /* always four urbs for sync */	8	#define SYNC_URBS 4 /* always four urbs for sync */
9	#define MAX_QUEUE 24 /* try not to exceed this queue length, in ms */	9	#define MAX_QUEUE 18 /* try not to exceed this queue length, in ms */
10		10
11	struct audioformat {	11	struct audioformat {
12	struct list_head list;	12	struct list_head list;
@@ -87,6 +87,7 @@ struct snd_usb_endpoint {
87	unsigned int phase; /* phase accumulator */	87	unsigned int phase; /* phase accumulator */
88	unsigned int maxpacksize; /* max packet size in bytes */	88	unsigned int maxpacksize; /* max packet size in bytes */
89	unsigned int maxframesize; /* max packet size in frames */	89	unsigned int maxframesize; /* max packet size in frames */
		90	unsigned int max_urb_frames; /* max URB size in frames */
90	unsigned int curpacksize; /* current packet size in bytes (for capture) */	91	unsigned int curpacksize; /* current packet size in bytes (for capture) */
91	unsigned int curframesize; /* current packet size in frames (for capture) */	92	unsigned int curframesize; /* current packet size in frames (for capture) */
92	unsigned int syncmaxsize; /* sync endpoint packet size */	93	unsigned int syncmaxsize; /* sync endpoint packet size */
@@ -116,6 +117,8 @@ struct snd_usb_substream {
116	unsigned int channels_max; /* max channels in the all audiofmts */	117	unsigned int channels_max; /* max channels in the all audiofmts */
117	unsigned int cur_rate; /* current rate (for hw_params callback) */	118	unsigned int cur_rate; /* current rate (for hw_params callback) */
118	unsigned int period_bytes; /* current period bytes (for hw_params callback) */	119	unsigned int period_bytes; /* current period bytes (for hw_params callback) */
		120	unsigned int period_frames; /* current frames per period */
		121	unsigned int buffer_periods; /* current periods per buffer */
119	unsigned int altset_idx; /* USB data format: index of alternate setting */	122	unsigned int altset_idx; /* USB data format: index of alternate setting */
120	unsigned int txfr_quirk:1; /* allow sub-frame alignment */	123	unsigned int txfr_quirk:1; /* allow sub-frame alignment */
121	unsigned int fmt_type; /* USB audio format type (1-3) */	124	unsigned int fmt_type; /* USB audio format type (1-3) */
@@ -125,6 +128,7 @@ struct snd_usb_substream {
125		128
126	unsigned int hwptr_done; /* processed byte position in the buffer */	129	unsigned int hwptr_done; /* processed byte position in the buffer */
127	unsigned int transfer_done; /* processed frames since last period update */	130	unsigned int transfer_done; /* processed frames since last period update */
		131	unsigned int frame_limit; /* limits number of packets in URB */
128		132
129	/* data and sync endpoints for this stream */	133	/* data and sync endpoints for this stream */
130	unsigned int ep_num; /* the endpoint number */	134	unsigned int ep_num; /* the endpoint number */


diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index 93e970f2b3c0..21dc6422d747 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c
@@ -574,11 +574,14 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep,
574	snd_pcm_format_t pcm_format,	574	snd_pcm_format_t pcm_format,
575	unsigned int channels,	575	unsigned int channels,
576	unsigned int period_bytes,	576	unsigned int period_bytes,
		577	unsigned int frames_per_period,
		578	unsigned int periods_per_buffer,
577	struct audioformat *fmt,	579	struct audioformat *fmt,
578	struct snd_usb_endpoint *sync_ep)	580	struct snd_usb_endpoint *sync_ep)
579	{	581	{
580	unsigned int maxsize, i, urb_packs, total_packs, packs_per_ms;	582	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
581	int is_playback = usb_pipeout(ep->pipe);	583	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
		584	unsigned int max_urbs, i;
582	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;	585	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
583		586
584	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {	587	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
@@ -611,58 +614,67 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep,
611	else	614	else
612	ep->curpacksize = maxsize;	615	ep->curpacksize = maxsize;
613		616
614	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL)	617	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
615	packs_per_ms = 8 >> ep->datainterval;	618	packs_per_ms = 8 >> ep->datainterval;
616	else	619	max_packs_per_urb = MAX_PACKS_HS;
617	packs_per_ms = 1;
618
619	if (is_playback && !snd_usb_endpoint_implicit_feedback_sink(ep)) {
620	urb_packs = max(ep->chip->nrpacks, 1);
621	urb_packs = min(urb_packs, (unsigned int) MAX_PACKS);
622	} else {	620	} else {
623	urb_packs = 1;	621	packs_per_ms = 1;
		622	max_packs_per_urb = MAX_PACKS;
624	}	623	}
		624	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
		625	max_packs_per_urb = min(max_packs_per_urb,
		626	1U << sync_ep->syncinterval);
		627	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
625		628
626	urb_packs *= packs_per_ms;	629	/*
		630	* Capture endpoints need to use small URBs because there's no way
		631	* to tell in advance where the next period will end, and we don't
		632	* want the next URB to complete much after the period ends.
		633	*
		634	* Playback endpoints with implicit sync much use the same parameters
		635	* as their corresponding capture endpoint.
		636	*/
		637	if (usb_pipein(ep->pipe) \|\|
		638	snd_usb_endpoint_implicit_feedback_sink(ep)) {
627		639
628	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))	640	/* make capture URBs <= 1 ms and smaller than a period */
629	urb_packs = min(urb_packs, 1U << sync_ep->syncinterval);	641	urb_packs = min(max_packs_per_urb, packs_per_ms);
		642	while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
		643	urb_packs >>= 1;
		644	ep->nurbs = MAX_URBS;
630		645
631	/* decide how many packets to be used */	646	/*
632	if (is_playback && !snd_usb_endpoint_implicit_feedback_sink(ep)) {	647	* Playback endpoints without implicit sync are adjusted so that
633	unsigned int minsize, maxpacks;	648	* a period fits as evenly as possible in the smallest number of
		649	* URBs. The total number of URBs is adjusted to the size of the
		650	* ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
		651	*/
		652	} else {
634	/* determine how small a packet can be */	653	/* determine how small a packet can be */
635	minsize = (ep->freqn >> (16 - ep->datainterval))	654	minsize = (ep->freqn >> (16 - ep->datainterval)) *
636	* (frame_bits >> 3);	655	(frame_bits >> 3);
637	/* with sync from device, assume it can be 12% lower */	656	/* with sync from device, assume it can be 12% lower */
638	if (sync_ep)	657	if (sync_ep)
639	minsize -= minsize >> 3;	658	minsize -= minsize >> 3;
640	minsize = max(minsize, 1u);	659	minsize = max(minsize, 1u);
641	total_packs = (period_bytes + minsize - 1) / minsize;
642	/* we need at least two URBs for queueing */
643	if (total_packs < 2) {
644	total_packs = 2;
645	} else {
646	/* and we don't want too long a queue either */
647	maxpacks = max(MAX_QUEUE * packs_per_ms, urb_packs * 2);
648	total_packs = min(total_packs, maxpacks);
649	}
650	} else {
651	while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
652	urb_packs >>= 1;
653	total_packs = MAX_URBS * urb_packs;
654	}
655		660
656	ep->nurbs = (total_packs + urb_packs - 1) / urb_packs;	661	/* how many packets will contain an entire ALSA period? */
657	if (ep->nurbs > MAX_URBS) {	662	max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);
658	/* too much... */	663
659	ep->nurbs = MAX_URBS;	664	/* how many URBs will contain a period? */
660	total_packs = MAX_URBS * urb_packs;	665	urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
661	} else if (ep->nurbs < 2) {	666	max_packs_per_urb);
662	/* too little - we need at least two packets	667	/* how many packets are needed in each URB? */
663	* to ensure contiguous playback/capture	668	urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
664	*/	669
665	ep->nurbs = 2;	670	/* limit the number of frames in a single URB */
		671	ep->max_urb_frames = DIV_ROUND_UP(frames_per_period,
		672	urbs_per_period);
		673
		674	/* try to use enough URBs to contain an entire ALSA buffer */
		675	max_urbs = min((unsigned) MAX_URBS,
		676	MAX_QUEUE * packs_per_ms / urb_packs);
		677	ep->nurbs = min(max_urbs, urbs_per_period * periods_per_buffer);
666	}	678	}
667		679
668	/* allocate and initialize data urbs */	680	/* allocate and initialize data urbs */
@@ -670,8 +682,7 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep,
670	struct snd_urb_ctx *u = &ep->urb[i];	682	struct snd_urb_ctx *u = &ep->urb[i];
671	u->index = i;	683	u->index = i;
672	u->ep = ep;	684	u->ep = ep;
673	u->packets = (i + 1) * total_packs / ep->nurbs	685	u->packets = urb_packs;
674	- i * total_packs / ep->nurbs;
675	u->buffer_size = maxsize * u->packets;	686	u->buffer_size = maxsize * u->packets;
676		687
677	if (fmt->fmt_type == UAC_FORMAT_TYPE_II)	688	if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
@@ -748,6 +759,8 @@ out_of_memory:
748	* @pcm_format: the audio fomat.	759	* @pcm_format: the audio fomat.
749	* @channels: the number of audio channels.	760	* @channels: the number of audio channels.
750	* @period_bytes: the number of bytes in one alsa period.	761	* @period_bytes: the number of bytes in one alsa period.
		762	* @period_frames: the number of frames in one alsa period.
		763	* @buffer_periods: the number of periods in one alsa buffer.
751	* @rate: the frame rate.	764	* @rate: the frame rate.
752	* @fmt: the USB audio format information	765	* @fmt: the USB audio format information
753	* @sync_ep: the sync endpoint to use, if any	766	* @sync_ep: the sync endpoint to use, if any
@@ -760,6 +773,8 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
760	snd_pcm_format_t pcm_format,	773	snd_pcm_format_t pcm_format,
761	unsigned int channels,	774	unsigned int channels,
762	unsigned int period_bytes,	775	unsigned int period_bytes,
		776	unsigned int period_frames,
		777	unsigned int buffer_periods,
763	unsigned int rate,	778	unsigned int rate,
764	struct audioformat *fmt,	779	struct audioformat *fmt,
765	struct snd_usb_endpoint *sync_ep)	780	struct snd_usb_endpoint *sync_ep)
@@ -793,7 +808,8 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
793	switch (ep->type) {	808	switch (ep->type) {
794	case SND_USB_ENDPOINT_TYPE_DATA:	809	case SND_USB_ENDPOINT_TYPE_DATA:
795	err = data_ep_set_params(ep, pcm_format, channels,	810	err = data_ep_set_params(ep, pcm_format, channels,
796	period_bytes, fmt, sync_ep);	811	period_bytes, period_frames,
		812	buffer_periods, fmt, sync_ep);
797	break;	813	break;
798	case SND_USB_ENDPOINT_TYPE_SYNC:	814	case SND_USB_ENDPOINT_TYPE_SYNC:
799	err = sync_ep_set_params(ep, fmt);	815	err = sync_ep_set_params(ep, fmt);


diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h index 2287adf5ca59..3bd02f0d226c 100644 --- a/sound/usb/endpoint.h +++ b/sound/usb/endpoint.h
@@ -12,6 +12,8 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
12	snd_pcm_format_t pcm_format,	12	snd_pcm_format_t pcm_format,
13	unsigned int channels,	13	unsigned int channels,
14	unsigned int period_bytes,	14	unsigned int period_bytes,
		15	unsigned int period_frames,
		16	unsigned int buffer_periods,
15	unsigned int rate,	17	unsigned int rate,
16	struct audioformat *fmt,	18	struct audioformat *fmt,
17	struct snd_usb_endpoint *sync_ep);	19	struct snd_usb_endpoint *sync_ep);


diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index b375d58871e7..19e79953f2e3 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c
@@ -595,6 +595,7 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs)
595	subs->pcm_format,	595	subs->pcm_format,
596	subs->channels,	596	subs->channels,
597	subs->period_bytes,	597	subs->period_bytes,
		598	0, 0,
598	subs->cur_rate,	599	subs->cur_rate,
599	subs->cur_audiofmt,	600	subs->cur_audiofmt,
600	NULL);	601	NULL);
@@ -631,6 +632,7 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs)
631	subs->pcm_format,	632	subs->pcm_format,
632	sync_fp->channels,	633	sync_fp->channels,
633	sync_period_bytes,	634	sync_period_bytes,
		635	0, 0,
634	subs->cur_rate,	636	subs->cur_rate,
635	sync_fp,	637	sync_fp,
636	NULL);	638	NULL);
@@ -653,6 +655,8 @@ static int configure_endpoint(struct snd_usb_substream *subs)
653	subs->pcm_format,	655	subs->pcm_format,
654	subs->channels,	656	subs->channels,
655	subs->period_bytes,	657	subs->period_bytes,
		658	subs->period_frames,
		659	subs->buffer_periods,
656	subs->cur_rate,	660	subs->cur_rate,
657	subs->cur_audiofmt,	661	subs->cur_audiofmt,
658	subs->sync_endpoint);	662	subs->sync_endpoint);
@@ -689,6 +693,8 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
689		693
690	subs->pcm_format = params_format(hw_params);	694	subs->pcm_format = params_format(hw_params);
691	subs->period_bytes = params_period_bytes(hw_params);	695	subs->period_bytes = params_period_bytes(hw_params);
		696	subs->period_frames = params_period_size(hw_params);
		697	subs->buffer_periods = params_periods(hw_params);
692	subs->channels = params_channels(hw_params);	698	subs->channels = params_channels(hw_params);
693	subs->cur_rate = params_rate(hw_params);	699	subs->cur_rate = params_rate(hw_params);
694		700
@@ -1363,6 +1369,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
1363	frames = 0;	1369	frames = 0;
1364	urb->number_of_packets = 0;	1370	urb->number_of_packets = 0;
1365	spin_lock_irqsave(&subs->lock, flags);	1371	spin_lock_irqsave(&subs->lock, flags);
		1372	subs->frame_limit += ep->max_urb_frames;
1366	for (i = 0; i < ctx->packets; i++) {	1373	for (i = 0; i < ctx->packets; i++) {
1367	if (ctx->packet_size[i])	1374	if (ctx->packet_size[i])
1368	counts = ctx->packet_size[i];	1375	counts = ctx->packet_size[i];
@@ -1377,6 +1384,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
1377	subs->transfer_done += counts;	1384	subs->transfer_done += counts;
1378	if (subs->transfer_done >= runtime->period_size) {	1385	if (subs->transfer_done >= runtime->period_size) {
1379	subs->transfer_done -= runtime->period_size;	1386	subs->transfer_done -= runtime->period_size;
		1387	subs->frame_limit = 0;
1380	period_elapsed = 1;	1388	period_elapsed = 1;
1381	if (subs->fmt_type == UAC_FORMAT_TYPE_II) {	1389	if (subs->fmt_type == UAC_FORMAT_TYPE_II) {
1382	if (subs->transfer_done > 0) {	1390	if (subs->transfer_done > 0) {
@@ -1399,8 +1407,10 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
1399	break;	1407	break;
1400	}	1408	}
1401	}	1409	}
1402	if (period_elapsed &&	1410	/* finish at the period boundary or after enough frames */
1403	!snd_usb_endpoint_implicit_feedback_sink(subs->data_endpoint)) /* finish at the period boundary */	1411	if ((period_elapsed \|\|
		1412	subs->transfer_done >= subs->frame_limit) &&
		1413	!snd_usb_endpoint_implicit_feedback_sink(ep))
1404	break;	1414	break;
1405	}	1415	}
1406	bytes = frames * ep->stride;	1416	bytes = frames * ep->stride;


diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h index caabe9b3af49..5d2fe0530745 100644 --- a/sound/usb/usbaudio.h +++ b/sound/usb/usbaudio.h
@@ -55,7 +55,6 @@ struct snd_usb_audio {
55	struct list_head mixer_list; /* list of mixer interfaces */	55	struct list_head mixer_list; /* list of mixer interfaces */
56		56
57	int setup; /* from the 'device_setup' module param */	57	int setup; /* from the 'device_setup' module param */
58	int nrpacks; /* from the 'nrpacks' module param */
59	bool autoclock; /* from the 'autoclock' module param */	58	bool autoclock; /* from the 'autoclock' module param */
60		59
61	struct usb_host_interface ctrl_intf; / the audio control interface */	60	struct usb_host_interface ctrl_intf; / the audio control interface */