[ALSA] Remove PCM xfer_align sw params

The xfer_align sw_params parameter has never been used in a sane manner,
and no one understands what this does exactly.  The current
implementation looks also buggy because it allows write of shorter size
than xfer_align.  So, if you do partial writes, the write isn't actually
aligned at all.
Removing this parameter will make some pcm_lib_* code more readable
(and less buggy).

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

7 files changed, 5 insertions, 32 deletions

diff --git a/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl b/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
index 48e4053eda12..835e320eeb4d 100644
--- a/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
+++ b/Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl
@@ -2188,7 +2188,6 @@ struct _snd_pcm_runtime {
         struct timespec tstamp_mode;    /* mmap timestamp is updated */
         unsigned int period_step;
         unsigned int sleep_min;         /* min ticks to sleep */
-        snd_pcm_uframes_t xfer_align;   /* xfer size need to be a multiple */
         snd_pcm_uframes_t start_threshold;
         snd_pcm_uframes_t stop_threshold;
         snd_pcm_uframes_t silence_threshold; /* Silence filling happens when
diff --git a/include/sound/asound.h b/include/sound/asound.h
index ee753d782e2d..069d9120e622 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -363,7 +363,7 @@ struct snd_pcm_sw_params {
         unsigned int period_step;
         unsigned int sleep_min;                 /* min ticks to sleep */
         snd_pcm_uframes_t avail_min;            /* min avail frames for wakeup */
-        snd_pcm_uframes_t xfer_align;           /* xfer size need to be a multiple */
+        snd_pcm_uframes_t xfer_align;           /* obsolete: xfer size need to be a multiple */
         snd_pcm_uframes_t start_threshold;      /* min hw_avail frames for automatic start */
         snd_pcm_uframes_t stop_threshold;       /* min avail frames for automatic stop */
         snd_pcm_uframes_t silence_threshold;    /* min distance from noise for silence filling */
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 65f636223d39..1270cbce776a 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -287,7 +287,6 @@ struct snd_pcm_runtime {
         int tstamp_mode;                /* mmap timestamp is updated */
         unsigned int period_step;
         unsigned int sleep_min;         /* min ticks to sleep */
-        snd_pcm_uframes_t xfer_align;   /* xfer size need to be a multiple */
         snd_pcm_uframes_t start_threshold;
         snd_pcm_uframes_t stop_threshold;
         snd_pcm_uframes_t silence_threshold; /* Silence filling happens when
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index d0c4ceb9f0b4..be089ccd736d 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -988,7 +988,6 @@ static int snd_pcm_oss_change_params(struct snd_pcm_substream *substream)
         sw_params->sleep_min = 0;
         sw_params->avail_min = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ?
                 1 : runtime->period_size;
-        sw_params->xfer_align = 1;
         if (atomic_read(&substream->mmap_count) ||
             substream->oss.setup.nosilence) {
                 sw_params->silence_threshold = 0;
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index cf9b9493d41d..97cb681502a3 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -389,7 +389,6 @@ static void snd_pcm_substream_proc_sw_params_read(struct snd_info_entry *entry,
         snd_iprintf(buffer, "period_step: %u\n", runtime->period_step);
         snd_iprintf(buffer, "sleep_min: %u\n", runtime->sleep_min);
         snd_iprintf(buffer, "avail_min: %lu\n", runtime->control->avail_min);
-        snd_iprintf(buffer, "xfer_align: %lu\n", runtime->xfer_align);
         snd_iprintf(buffer, "start_threshold: %lu\n", runtime->start_threshold);
         snd_iprintf(buffer, "stop_threshold: %lu\n", runtime->stop_threshold);
         snd_iprintf(buffer, "silence_threshold: %lu\n", runtime->silence_threshold);
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index f9f9b3fe956e..c1c1556105c0 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1628,8 +1628,6 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
 
         if (size == 0)
                 return 0;
-        if (size > runtime->xfer_align)
-                size -= size % runtime->xfer_align;
 
         snd_pcm_stream_lock_irq(substream);
         switch (runtime->status->state) {
@@ -1657,9 +1655,7 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
                 avail = snd_pcm_playback_avail(runtime);
                 if (!avail ||
                     (snd_pcm_running(substream) &&
-                     ((avail < runtime->control->avail_min && size > avail) ||
-                      (size >= runtime->xfer_align &&
-                       avail < runtime->xfer_align)))) {
+                     (avail < runtime->control->avail_min && size > avail))) {
                         wait_queue_t wait;
                         enum { READY, SIGNALED, ERROR, SUSPENDED, EXPIRED, DROPPED } state;
                         long tout;
@@ -1731,8 +1727,6 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
                                 break;
                         }
                 }
-                if (avail > runtime->xfer_align)
-                        avail -= avail % runtime->xfer_align;
                 frames = size > avail ? avail : size;
                 cont = runtime->buffer_size - runtime->control->appl_ptr % runtime->buffer_size;
                 if (frames > cont)
@@ -1900,8 +1894,6 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
 
         if (size == 0)
                 return 0;
-        if (size > runtime->xfer_align)
-                size -= size % runtime->xfer_align;
 
         snd_pcm_stream_lock_irq(substream);
         switch (runtime->status->state) {
@@ -1936,12 +1928,12 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
               __draining:
                 avail = snd_pcm_capture_avail(runtime);
                 if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
-                        if (avail < runtime->xfer_align) {
+                        if (!avail) {
                                 err = -EPIPE;
                                 goto _end_unlock;
                         }
-                } else if ((avail < runtime->control->avail_min && size > avail) ||
-                           (size >= runtime->xfer_align && avail < runtime->xfer_align)) {
+                } else if (avail < runtime->control->avail_min &&
+                           size > avail) {
                         wait_queue_t wait;
                         enum { READY, SIGNALED, ERROR, SUSPENDED, EXPIRED, DROPPED } state;
                         long tout;
@@ -2014,8 +2006,6 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
                                 break;
                         }
                 }
-                if (avail > runtime->xfer_align)
-                        avail -= avail % runtime->xfer_align;
                 frames = size > avail ? avail : size;
                 cont = runtime->buffer_size - runtime->control->appl_ptr % runtime->buffer_size;
                 if (frames > cont)
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 3fc33deabe35..3c22d78ee8f4 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -435,7 +435,6 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
         runtime->period_step = 1;
         runtime->sleep_min = 0;
         runtime->control->avail_min = runtime->period_size;
-        runtime->xfer_align = runtime->period_size;
         runtime->start_threshold = 1;
         runtime->stop_threshold = runtime->buffer_size;
         runtime->silence_threshold = 0;
@@ -532,9 +531,6 @@ static int snd_pcm_sw_params(struct snd_pcm_substream *substream,
                 return -EINVAL;
         if (params->avail_min == 0)
                 return -EINVAL;
-        if (params->xfer_align == 0 ||
-            params->xfer_align % runtime->min_align != 0)
-                return -EINVAL;
         if (params->silence_size >= runtime->boundary) {
                 if (params->silence_threshold != 0)
                         return -EINVAL;
@@ -553,7 +549,6 @@ static int snd_pcm_sw_params(struct snd_pcm_substream *substream,
         runtime->stop_threshold = params->stop_threshold;
         runtime->silence_threshold = params->silence_threshold;
         runtime->silence_size = params->silence_size;
-        runtime->xfer_align = params->xfer_align;
         params->boundary = runtime->boundary;
         if (snd_pcm_running(substream)) {
                 if (runtime->sleep_min)
@@ -2239,8 +2234,6 @@ static snd_pcm_sframes_t snd_pcm_playback_rewind(struct snd_pcm_substream *subst
         }
         if (frames > (snd_pcm_uframes_t)hw_avail)
                 frames = hw_avail;
-        else
-                frames -= frames % runtime->xfer_align;
         appl_ptr = runtime->control->appl_ptr - frames;
         if (appl_ptr < 0)
                 appl_ptr += runtime->boundary;
@@ -2289,8 +2282,6 @@ static snd_pcm_sframes_t snd_pcm_capture_rewind(struct snd_pcm_substream *substr
         }
         if (frames > (snd_pcm_uframes_t)hw_avail)
                 frames = hw_avail;
-        else
-                frames -= frames % runtime->xfer_align;
         appl_ptr = runtime->control->appl_ptr - frames;
         if (appl_ptr < 0)
                 appl_ptr += runtime->boundary;
@@ -2340,8 +2331,6 @@ static snd_pcm_sframes_t snd_pcm_playback_forward(struct snd_pcm_substream *subs
         }
         if (frames > (snd_pcm_uframes_t)avail)
                 frames = avail;
-        else
-                frames -= frames % runtime->xfer_align;
         appl_ptr = runtime->control->appl_ptr + frames;
         if (appl_ptr >= (snd_pcm_sframes_t)runtime->boundary)
                 appl_ptr -= runtime->boundary;
@@ -2391,8 +2380,6 @@ static snd_pcm_sframes_t snd_pcm_capture_forward(struct snd_pcm_substream *subst
         }
         if (frames > (snd_pcm_uframes_t)avail)
                 frames = avail;
-        else
-                frames -= frames % runtime->xfer_align;
         appl_ptr = runtime->control->appl_ptr + frames;
         if (appl_ptr >= (snd_pcm_sframes_t)runtime->boundary)
                 appl_ptr -= runtime->boundary;