On 20.04.2022 12:15, Sascha Hauer wrote:
EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
Hi,
Hi Sascha,
On Mon, Mar 07, 2022 at 02:21:57PM +0200, Codrin Ciubotariu wrote:
Even if struct snd_dmaengine_pcm_config is used, prepare_slave_config() callback might not be set. Check if this callback is set before using it.
Fixes: fa654e085300 ("ASoC: dmaengine-pcm: Provide default config") Signed-off-by: Codrin Ciubotariu codrin.ciubotariu@microchip.com
Changes in v2,v3:
- none
sound/soc/soc-generic-dmaengine-pcm.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c index 285441d6aeed..2ab2ddc1294d 100644 --- a/sound/soc/soc-generic-dmaengine-pcm.c +++ b/sound/soc/soc-generic-dmaengine-pcm.c @@ -86,10 +86,10 @@ static int dmaengine_pcm_hw_params(struct snd_soc_component *component,
memset(&slave_config, 0, sizeof(slave_config));
if (!pcm->config)prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config;else
if (pcm->config && pcm->config->prepare_slave_config) prepare_slave_config = pcm->config->prepare_slave_config;elseprepare_slave_config = snd_dmaengine_pcm_prepare_slave_config; if (prepare_slave_config) { int ret = prepare_slave_config(substream, params, &slave_config);I wonder if this patch is correct. There are drivers like sound/soc/mxs/mxs-pcm.c which call snd_dmaengine_pcm_register() with a config which has the prepare_slave_config callback unset. For these drivers dmaengine_pcm_hw_params() previously was a no-op. Now with this patch snd_dmaengine_pcm_prepare_slave_config() and dmaengine_slave_config() are called. At least for the mxs-pcm driver calling dmaengine_slave_config() will return -ENOSYS.
At least the "Check if this callback is set before using it" part is wrong, the callback is checked before using it with
if (prepare_slave_config) { ... }I don't have any mxs hardware at hand to test this. I just stumbled upon the change of behaviour when rebasing https://patchwork.kernel.org/project/alsa-devel/patch/20220301122111.1073174... on current master.
You are right. I changed the behavior from: if (pmc->config && !pcm->config->prepare_slave_config) <do nothing> to: if (pmc->config && !pcm->config->prepare_slave_config) snd_dmaengine_pcm_prepare_slave_config()
It was not intended and I agree that the commit message is not accurate. I guess some drivers might not need dmaengine_slave_config()... However, in my case, for the mchp-pdmc driver, I do have pcm->config with pcm->config->prepare_slave_config NULL, but I still need snd_dmaengine_pcm_prepare_slave_config() to be called. Should we add a separate flag to call snd_dmaengine_pcm_prepare_slave_config() if pcm->config->prepare_slave_config is NULL?
Nice catch!
Best regards, Codrin