Re: [alsa-devel] [PATCH] [PATCH v2] ALSA: hda: Retry codec read on first time failure

[Takashi Iwai <tiwai@suse.de>]

On Fri, 30 Aug 2019 07:23:18 +0200,
vani.ganji@intel.com wrote:
> 
> From: Vani Ganji <vani.ganji@intel.com>
> 
> Sometimes HDMI audio fails while fast switching
> between HDMI and Speaker due to codec Get Power state verb read failure.
> 
> Verb is codec driver to access codec HW. Since issue scenario involves
> fast switching between HDMI and speaker, there might be chance to fail
> read from HW and same happened in the error scenario.
> 
> Based on Display/Graphics architect suggestion, added a retry mechanism
> for failure on first attempt.
> 
> Changes from v1:
> -Corrected missing braces.
> 
> Signed-off-by: Vani Ganji <vani.ganji@intel.com>

Do you still need this even with the very latest upstream code?
As mentioned, the recent change to use the sync-write should reduce
such errors.

If it's about the SOF/SST, you can try to set the hdac_bus.sync_write
flag in the corresponding drivers, too.


thanks,

Takashi

> ---
>  sound/hda/hdac_device.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c
> index b26cc93e7e10..3874d54aa686 100644
> --- a/sound/hda/hdac_device.c
> +++ b/sound/hda/hdac_device.c
> @@ -984,10 +984,17 @@ static unsigned int codec_read(struct hdac_device *hdac, hda_nid_t nid,
>  {
>  	unsigned int cmd = snd_hdac_make_cmd(hdac, nid, verb, parm);
>  	unsigned int res;
> -
> -	if (snd_hdac_exec_verb(hdac, cmd, flags, &res))
> -		return -1;
> -
> +	unsigned int count;
> +
> +	/* Retry verb once more if it fails first time */
> +	/* recommended to retry since it is HW related */
> +	for (count = 0; count <= 1; count++) {
> +		if (snd_hdac_exec_verb(hdac, cmd, flags, &res)) {
> +			if (count == 1)
> +				return -1;
> +		} else
> +			break;
> +	}
>  	return res;
>  }
>  
> -- 
> 2.17.1
> 
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