ALSA: PCM midlevel: improve fifo_size handling

Move the fifo_size assignment to hw->ioctl callback to allow lowlevel
drivers overwrite the default behaviour.

fifo_size is in frames not bytes as specified in asound.h and alsa-lib's
documentation, but most hardware have fixed byte based FIFOs. Introduce
internal SNDRV_PCM_INFO_FIFO_IN_FRAMES.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

4 files changed, 33 insertions, 3 deletions

diff --git a/include/sound/asound.h b/include/sound/asound.h
index 6add80fc2512..82aed3f47534 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -255,6 +255,7 @@ typedef int __bitwise snd_pcm_subformat_t;
 #define SNDRV_PCM_INFO_HALF_DUPLEX      0x00100000      /* only half duplex */
 #define SNDRV_PCM_INFO_JOINT_DUPLEX     0x00200000      /* playback and capture stream are somewhat correlated */
 #define SNDRV_PCM_INFO_SYNC_START       0x00400000      /* pcm support some kind of sync go */
+#define SNDRV_PCM_INFO_FIFO_IN_FRAMES   0x80000000      /* internal kernel flag - FIFO size is in frames */
 
 typedef int __bitwise snd_pcm_state_t;
 #define SNDRV_PCM_STATE_OPEN            ((__force snd_pcm_state_t) 0) /* stream is open */
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 267effddb070..8a69b5c1e1c4 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -98,6 +98,7 @@ struct snd_pcm_ops {
 #define SNDRV_PCM_IOCTL1_INFO           1
 #define SNDRV_PCM_IOCTL1_CHANNEL_INFO   2
 #define SNDRV_PCM_IOCTL1_GSTATE         3
+#define SNDRV_PCM_IOCTL1_FIFO_SIZE      4
 
 #define SNDRV_PCM_TRIGGER_STOP          0
 #define SNDRV_PCM_TRIGGER_START         1
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index d659995ac3ac..adc2b0bd1132 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1524,6 +1524,23 @@ static int snd_pcm_lib_ioctl_channel_info(struct snd_pcm_substream *substream,
         return 0;
 }
 
+static int snd_pcm_lib_ioctl_fifo_size(struct snd_pcm_substream *substream,
+                                       void *arg)
+{
+        struct snd_pcm_hw_params *params = arg;
+        snd_pcm_format_t format;
+        int channels, width;
+
+        params->fifo_size = substream->runtime->hw.fifo_size;
+        if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_FIFO_IN_FRAMES)) {
+                format = params_format(params);
+                channels = params_channels(params);
+                width = snd_pcm_format_physical_width(format);
+                params->fifo_size /= width * channels;
+        }
+        return 0;
+}
+
 /**
  * snd_pcm_lib_ioctl - a generic PCM ioctl callback
  * @substream: the pcm substream instance
@@ -1545,6 +1562,8 @@ int snd_pcm_lib_ioctl(struct snd_pcm_substream *substream,
                 return snd_pcm_lib_ioctl_reset(substream, arg);
         case SNDRV_PCM_IOCTL1_CHANNEL_INFO:
                 return snd_pcm_lib_ioctl_channel_info(substream, arg);
+        case SNDRV_PCM_IOCTL1_FIFO_SIZE:
+                return snd_pcm_lib_ioctl_fifo_size(substream, arg);
         }
         return -ENXIO;
 }
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 45dc53fcfa2f..84da3ba17c86 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -312,9 +312,18 @@ int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
 
         hw = &substream->runtime->hw;
         if (!params->info)
-                params->info = hw->info;
-        if (!params->fifo_size)
-                params->fifo_size = hw->fifo_size;
+                params->info = hw->info & ~SNDRV_PCM_INFO_FIFO_IN_FRAMES;
+        if (!params->fifo_size) {
+                if (snd_mask_min(&params->masks[SNDRV_PCM_HW_PARAM_FORMAT]) ==
+                    snd_mask_max(&params->masks[SNDRV_PCM_HW_PARAM_FORMAT]) &&
+                    snd_mask_min(&params->masks[SNDRV_PCM_HW_PARAM_CHANNELS]) ==
+                    snd_mask_max(&params->masks[SNDRV_PCM_HW_PARAM_CHANNELS])) {
+                        changed = substream->ops->ioctl(substream,
+                                        SNDRV_PCM_IOCTL1_FIFO_SIZE, params);
+                        if (params < 0)
+                                return changed;
+                }
+        }
         params->rmask = 0;
         return 0;
 }