RE: [PATCH] ASoC: fsl_asrc: add protection for the asrc of older version

Hi

Hi Shengjiu,

On Fri, Mar 01, 2019 at 02:32:38AM +0000, S.j. Wang wrote:

quoted

There is a constraint for the channel number setting on the asrc of
older version (e.g. imx35), the channel number should be even, odd
number isn't valid.

So add protection when the asrc of older version is used.

Signed-off-by: Shengjiu Wang <redacted>
---
 sound/soc/fsl/fsl_asrc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/soc/fsl/fsl_asrc.c b/sound/soc/fsl/fsl_asrc.c index

528e8b108422..b3b3c5e15ef1 100644

--- a/sound/soc/fsl/fsl_asrc.c
+++ b/sound/soc/fsl/fsl_asrc.c

@@ -109,7 +109,8 @@ static int fsl_asrc_request_pair(int channels, struct

fsl_asrc_pair *pair)

quoted

 	if (index == ASRC_INVALID_PAIR) {
 		dev_err(dev, "all pairs are busy now\n");
 		ret = -EBUSY;
-	} else if (asrc_priv->channel_avail < channels) {
+	} else if (asrc_priv->channel_avail < channels ||
+		(asrc_priv->channel_bits < 4 && channels % 2 != 0)) {
 		dev_err(dev, "can't afford required channels: %d\n",

channels);

I feel it'd be better to have another else-if, since the existing error message
is against something else.

+	} else if (asrc_priv->channel_bits < 4 && channels & 1) {
+		/* old version of ASRC has channel_bits = 3 */
+  		dev_err(dev, "does not support odd channel number\n");
+  		ret = -EINVAL;

Alternatively, I feel instead of error-out at here, should we add a HW
constraint or at least fence it off at the beginning of the hw_params()? This
is actually nothing specific to the pair-request function but a hardware
constraint.

How about add constraint in startup?
static int fsl_asrc_dai_startup(struct snd_pcm_substream *substream,
                               struct snd_soc_dai *dai)
{
       struct fsl_asrc *asrc_priv = snd_soc_dai_get_drvdata(dai);

       if (asrc_priv->channel_bits == 3) {
               snd_pcm_hw_constraint_step(substream->runtime, 0,
                                          SNDRV_PCM_HW_PARAM_CHANNELS, 2);
       }

       return 0;
}

Best regards
Wang shengjiu