[PATCH 1/2] ALSA: hda: Set up BDL table at hw_params

[PATCH 1/2] ALSA: hda: Set up BDL table at hw_params

[Takashi Iwai]

So far the setup of BDL table is performed at the prepare stage, where
all PCM parameters have been already set up.  When something wrong
happens at it, we return -EINVAL; it's supposed to be a rare case
since the involved memory allocation is a small chunk of kmalloc for
the table.

However, when we receive too many small non-contiguous pages in highly
fragmented memories, it may overflow the max table size, resulting in
the same -EINVAL error from the prepare, too.  A bad scenario is that
user-space cannot know what went wrong (as it's an error from the
prepare stage) and -EINVAL, hence it may retry with the same
parameters, failing again repeatedly.

In this patch, we try to set up the BDL table at hw_params right after
the buffer allocation, and return -ENOMEM if it overflows.
This allows user-space knowing that it should reduce the buffer size
request accordingly and may retry with more fitting parameters.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/pci/hda/hda_controller.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/sound/pci/hda/hda_controller.c b/sound/pci/hda/hda_controller.c
index 3e7bfeee84fd..29eae7244fe7 100644
--- a/sound/pci/hda/hda_controller.c
+++ b/sound/pci/hda/hda_controller.c
@@ -24,6 +24,7 @@
 
 #include <sound/core.h>
 #include <sound/initval.h>
+#include <sound/pcm_params.h>
 #include "hda_controller.h"
 #include "hda_local.h"
 
@@ -108,6 +109,7 @@ static int azx_pcm_hw_params(struct snd_pcm_substream *substream,
 	struct azx_pcm *apcm = snd_pcm_substream_chip(substream);
 	struct azx *chip = apcm->chip;
 	struct azx_dev *azx_dev = get_azx_dev(substream);
+	struct hdac_stream *hdas = azx_stream(azx_dev);
 	int ret = 0;
 
 	trace_azx_pcm_hw_params(chip, azx_dev);
@@ -117,9 +119,15 @@ static int azx_pcm_hw_params(struct snd_pcm_substream *substream,
 		goto unlock;
 	}
 
-	azx_dev->core.bufsize = 0;
-	azx_dev->core.period_bytes = 0;
-	azx_dev->core.format_val = 0;
+	/* Set up BDLEs here, return -ENOMEM if too many BDLEs are required */
+	hdas->bufsize = params_buffer_bytes(hw_params);
+	hdas->period_bytes = params_period_bytes(hw_params);
+	hdas->format_val = 0;
+	hdas->no_period_wakeup =
+		(hw_params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP) &&
+		(hw_params->flags & SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP);
+	if (snd_hdac_stream_setup_periods(hdas) < 0)
+		ret = -ENOMEM;
 
 unlock:
 	dsp_unlock(azx_dev);
-- 
2.35.3

[PATCH 2/2] ALSA: hda: Downgrade BDL table overflow message

[Takashi Iwai]

When BDL table entry overflow happens, the driver spews an error
message explicitly.  But basically this condition can be triggered
easily by an application and it may flood of error logs
unnecessarily.

Downgrade the error message with dev_dbg() as a debug message
instead.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/hda/hdac_stream.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c
index 610ea7a33cd8..b53de020309f 100644
--- a/sound/hda/hdac_stream.c
+++ b/sound/hda/hdac_stream.c
@@ -567,7 +567,7 @@ int snd_hdac_stream_setup_periods(struct hdac_stream *azx_dev)
 	return 0;
 
  error:
-	dev_err(bus->dev, "Too many BDL entries: buffer=%d, period=%d\n",
+	dev_dbg(bus->dev, "Too many BDL entries: buffer=%d, period=%d\n",
 		azx_dev->bufsize, period_bytes);
 	return -EINVAL;
 }
-- 
2.35.3