[alsa-devel] [PATCH 2/2] ALSA: usb: handle descriptor with SYNC_NONE illegal value

[Takashi Iwai]

On Fri, 14 Aug 2015 00:42:33 +0200,
Pierre-Louis Bossart wrote:
> --- a/sound/usb/pcm.c
> +++ b/sound/usb/pcm.c
> @@ -411,10 +411,17 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
>  	if (altsd->bNumEndpoints < 2)
>  		return 0;
>  
> -	if ((is_playback && attr != USB_ENDPOINT_SYNC_ASYNC) ||
> +	if ((is_playback && attr == USB_ENDPOINT_SYNC_SYNC) ||
> +	    (is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE) ||

Better to be:
	    (is_playback && (attr == USB_ENDPOINT_SYNC_SYNC ||
			     attr == USB_ENDPOINT_SYNC_ADAPTIVE)) ||


>  	    (!is_playback && attr != USB_ENDPOINT_SYNC_ADAPTIVE))
>  		return 0;
>  
> +	/*
> +	 * In case of illegal SYNC_NONE for OUT endpoint, we keep going to see
> +	 * if we don't find a sync endpoint, as on M-Audio Transit. In case of
> +	 * error fall back to SYNC mode and don't create sync endpoint
> +	 */
> +
>  	/* check sync-pipe endpoint */
>  	/* ... and check descriptor size before accessing bSynchAddress
>  	   because there is a version of the SB Audigy 2 NX firmware lacking
> @@ -428,6 +435,8 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
>  			   get_endpoint(alts, 1)->bmAttributes,
>  			   get_endpoint(alts, 1)->bLength,
>  			   get_endpoint(alts, 1)->bSynchAddress);
> +		if (is_playback && attr == USB_ENDPOINT_SYNC_NONE)
> +			goto no_valid_sync_ep_found;

We handle this as a success case, so the error message should be
avoided for SYNC_NONE.  Also, it's fine just returning 0 here.

>  		return -EINVAL;
>  	}
>  	ep = get_endpoint(alts, 1)->bEndpointAddress;
> @@ -438,6 +447,8 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
>  			"%d:%d : invalid sync pipe. is_playback %d, ep %02x, bSynchAddress %02x\n",
>  			   fmt->iface, fmt->altsetting,
>  			   is_playback, ep, get_endpoint(alts, 0)->bSynchAddress);
> +		if (is_playback && attr == USB_ENDPOINT_SYNC_NONE)
> +			goto no_valid_sync_ep_found;

Ditto.


thanks,

Takashi