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authorPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>2021-11-19 17:08:50 -0600
committerMark Brown <broonie@kernel.org>2021-11-24 12:57:18 +0000
commitb456abe63f60ad93c83a526d33b71574bc32656c (patch)
tree94c85af14b3d80371e201924a4209673f2723423
parent0e888a74e52db369e19aec908131cf171079b306 (diff)
ALSA: pcm: introduce INFO_NO_REWINDS flag
When the hardware can only deal with a monotonically increasing appl_ptr, this flag can be set. In case the application requests a rewind, be it with a snd_pcm_rewind() or with a direct change of a mmap'ed pointer followed by a SNDRV_PCM_IOCTL_SYNC_PTR, this patch checks if a rewind occurred and returns an error. Credits to Takashi Iwai for identifying the path with SYNC_PTR and suggesting the pointer checks. Suggested-by: Takashi Iwai <tiwai@suse.de> Reviewed-by: Takashi Iwai <tiwai@suse.de> Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com> Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Link: https://lore.kernel.org/r/20211119230852.206310-3-pierre-louis.bossart@linux.intel.com Signed-off-by: Mark Brown <broonie@kernel.org>
-rw-r--r--include/uapi/sound/asound.h2
-rw-r--r--sound/core/pcm_lib.c14
2 files changed, 15 insertions, 1 deletions
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 5fbb79e30819..ff7e638221c5 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -300,7 +300,7 @@ typedef int __bitwise snd_pcm_subformat_t;
#define SNDRV_PCM_INFO_HAS_LINK_ESTIMATED_ATIME 0x04000000 /* report estimated link audio time */
#define SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME 0x08000000 /* report synchronized audio/system time */
#define SNDRV_PCM_INFO_EXPLICIT_SYNC 0x10000000 /* needs explicit sync of pointers and data */
-
+#define SNDRV_PCM_INFO_NO_REWINDS 0x20000000 /* hardware can only support monotonic changes of appl_ptr */
#define SNDRV_PCM_INFO_DRAIN_TRIGGER 0x40000000 /* internal kernel flag - trigger in drain */
#define SNDRV_PCM_INFO_FIFO_IN_FRAMES 0x80000000 /* internal kernel flag - FIFO size is in frames */
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index fdd992772b20..f2090025236b 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -2128,6 +2128,7 @@ int pcm_lib_apply_appl_ptr(struct snd_pcm_substream *substream,
{
struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_uframes_t old_appl_ptr = runtime->control->appl_ptr;
+ snd_pcm_sframes_t diff;
int ret;
if (old_appl_ptr == appl_ptr)
@@ -2135,6 +2136,19 @@ int pcm_lib_apply_appl_ptr(struct snd_pcm_substream *substream,
if (appl_ptr >= runtime->boundary)
return -EINVAL;
+ /*
+ * check if a rewind is requested by the application
+ */
+ if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) {
+ diff = appl_ptr - old_appl_ptr;
+ if (diff >= 0) {
+ if (diff > runtime->buffer_size)
+ return -EINVAL;
+ } else {
+ if (runtime->boundary + diff > runtime->buffer_size)
+ return -EINVAL;
+ }
+ }
runtime->control->appl_ptr = appl_ptr;
if (substream->ops->ack) {