[alsa-devel] [PATCH - DMA engine v2 1/1] ALSA: SOC: DMA: increment buffer pointer atomically
From: Andreas Pape apape@de.adit-jv.com
Setting pointer and afterwards check for wrap around leads to the possibility of returning the inconsistent pointer position. This patch increments buffer pointer atomically to avoid this issue.
Signed-off-by: Andreas Pape apape@de.adit-jv.com
Since commit: b7ae6f3 dmaengine implementation has been moved from ASoC to ALSA core. So change goes to sound/soc/soc-dmaengine-pcm.c, apply to sound/core/pcm_dmaengine.c now
cherry picked from ADIT v3.14 e2f803f("ALSA: SOC: DMA: increment buffer pointer atomically") Signed-off-by: Veeraiyan Chidambaram veeraiyan.chidambaram@in.bosch.com (cherry picked from ADIT v4.1 commit 9e7eff10a38157db75f12e032fc378d3104a2812) Signed-off-by: Takashi Sakamoto takashi.sakamoto@miraclelinux.com (cherry picked from ADIT v4.9 commit 66c00aa1e7cd3b077fc2e5a45a4594b86246cf78) Signed-off-by: Jiada Wang jiada_wang@mentor.com
Signed-off-by: Timo Wischer twischer@de.adit-jv.com ---
v1 can be found in http://mailman.alsa-project.org/pipermail/alsa-devel/2016-November/115277.ht...
diff --git a/sound/core/pcm_dmaengine.c b/sound/core/pcm_dmaengine.c index 8eb58c7..0a7ed85 100644 --- a/sound/core/pcm_dmaengine.c +++ b/sound/core/pcm_dmaengine.c @@ -139,12 +139,14 @@ EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_set_config_from_dai_data);
static void dmaengine_pcm_dma_complete(void *arg) { + unsigned int new_pos; struct snd_pcm_substream *substream = arg; struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
- prtd->pos += snd_pcm_lib_period_bytes(substream); - if (prtd->pos >= snd_pcm_lib_buffer_bytes(substream)) - prtd->pos = 0; + new_pos = READ_ONCE(prtd->pos) + snd_pcm_lib_period_bytes(substream); + if (new_pos >= snd_pcm_lib_buffer_bytes(substream)) + new_pos = 0; + WRITE_ONCE(prtd->pos, new_pos);
snd_pcm_period_elapsed(substream); } @@ -235,7 +237,7 @@ EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_trigger); snd_pcm_uframes_t snd_dmaengine_pcm_pointer_no_residue(struct snd_pcm_substream *substream) { struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream); - return bytes_to_frames(substream->runtime, prtd->pos); + return bytes_to_frames(substream->runtime, READ_ONCE(prtd->pos)); } EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_pointer_no_residue);
Hi all,
Any comments to the patch in [1]?
Should I change anything?
[1] http://mailman.alsa-project.org/pipermail/alsa-devel/2018-July/138319.html
Best regards
*Timo Wischer*
*A*dvanced *D*river *I*nformation *T*echnology GmbH Engineering Software Base (ADITG/ESB) Robert-Bosch-Str. 200 31139 Hildesheim Germany
Tel. +49 5121 49 6938 Fax +49 5121 49 6999 twischer@de.adit-jv.com
ADIT is a joint venture company of Robert Bosch GmbH/Robert Bosch Car Multimedia GmbH and DENSO Corporation Sitz: Hildesheim, Registergericht: Amtsgericht Hildesheim HRB 3438 Geschäftsführung: Wilhelm Grabow, Ken Yaguchi
On 07/19/2018 12:29 PM, twischer@de.adit-jv.com wrote:
From: Andreas Pape apape@de.adit-jv.com
Setting pointer and afterwards check for wrap around leads to the possibility of returning the inconsistent pointer position. This patch increments buffer pointer atomically to avoid this issue.
Signed-off-by: Andreas Pape apape@de.adit-jv.com
Since commit: b7ae6f3 dmaengine implementation has been moved from ASoC to ALSA core. So change goes to sound/soc/soc-dmaengine-pcm.c, apply to sound/core/pcm_dmaengine.c now
cherry picked from ADIT v3.14 e2f803f("ALSA: SOC: DMA: increment buffer pointer atomically") Signed-off-by: Veeraiyan Chidambaram veeraiyan.chidambaram@in.bosch.com (cherry picked from ADIT v4.1 commit 9e7eff10a38157db75f12e032fc378d3104a2812) Signed-off-by: Takashi Sakamoto takashi.sakamoto@miraclelinux.com (cherry picked from ADIT v4.9 commit 66c00aa1e7cd3b077fc2e5a45a4594b86246cf78) Signed-off-by: Jiada Wang jiada_wang@mentor.com
Signed-off-by: Timo Wischer twischer@de.adit-jv.com
v1 can be found in http://mailman.alsa-project.org/pipermail/alsa-devel/2016-November/115277.ht...
diff --git a/sound/core/pcm_dmaengine.c b/sound/core/pcm_dmaengine.c index 8eb58c7..0a7ed85 100644 --- a/sound/core/pcm_dmaengine.c +++ b/sound/core/pcm_dmaengine.c @@ -139,12 +139,14 @@ EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_set_config_from_dai_data);
static void dmaengine_pcm_dma_complete(void *arg) {
- unsigned int new_pos; struct snd_pcm_substream *substream = arg; struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
- prtd->pos += snd_pcm_lib_period_bytes(substream);
- if (prtd->pos >= snd_pcm_lib_buffer_bytes(substream))
prtd->pos = 0;
new_pos = READ_ONCE(prtd->pos) + snd_pcm_lib_period_bytes(substream);
if (new_pos >= snd_pcm_lib_buffer_bytes(substream))
new_pos = 0;WRITE_ONCE(prtd->pos, new_pos);
snd_pcm_period_elapsed(substream); }
@@ -235,7 +237,7 @@ EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_trigger); snd_pcm_uframes_t snd_dmaengine_pcm_pointer_no_residue(struct snd_pcm_substream *substream) { struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
- return bytes_to_frames(substream->runtime, prtd->pos);
- return bytes_to_frames(substream->runtime, READ_ONCE(prtd->pos)); } EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_pointer_no_residue);
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Timo Wischer -
twischer＠de.adit-jv.com