[PATCH v2 7/9] ALSA: usb-audio: remove is_playback from implicit feedback quirks

[PATCH v2 7/9] ALSA: usb-audio: remove is_playback from implicit feedback quirks

[Eldad Zack]

An implicit feedback endpoint can only be a capture source. The
consumer (sink) of the implicit feedback endpoint is therefore limited
to playback EPs.
Check if the target endpoint is a playback first and remove redundant
checks.

Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
---
 sound/usb/pcm.c | 40 +++++++++++++++++++---------------------
 1 file changed, 19 insertions(+), 21 deletions(-)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index bb2e0f5..af30e08 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -334,41 +334,39 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 {
 	struct usb_host_interface *alts;
 	struct usb_interface *iface;
-	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
 	int implicit_fb = 0;
 	unsigned int ep;
 
+	/* Implicit feedback sync EPs consumers are always playback EPs */
+	if (subs->direction != SNDRV_PCM_STREAM_PLAYBACK)
+		return 0;
+
 	switch (subs->stream->chip->usb_id) {
 	case USB_ID(0x0763, 0x2030): /* M-Audio Fast Track C400 */
 	case USB_ID(0x0763, 0x2031): /* M-Audio Fast Track C600 */
-		if (is_playback) {
-			implicit_fb = 1;
-			ep = 0x81;
-			iface = usb_ifnum_to_if(dev, 3);
+		implicit_fb = 1;
+		ep = 0x81;
+		iface = usb_ifnum_to_if(dev, 3);
 
-			if (!iface || iface->num_altsetting == 0)
-				return -EINVAL;
+		if (!iface || iface->num_altsetting == 0)
+			return -EINVAL;
 
-			alts = &iface->altsetting[1];
-			goto add_sync_ep;
-		}
+		alts = &iface->altsetting[1];
+		goto add_sync_ep;
 		break;
 	case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
 	case USB_ID(0x0763, 0x2081):
-		if (is_playback) {
-			implicit_fb = 1;
-			ep = 0x81;
-			iface = usb_ifnum_to_if(dev, 2);
+		implicit_fb = 1;
+		ep = 0x81;
+		iface = usb_ifnum_to_if(dev, 2);
 
-			if (!iface || iface->num_altsetting == 0)
-				return -EINVAL;
+		if (!iface || iface->num_altsetting == 0)
+			return -EINVAL;
 
-			alts = &iface->altsetting[1];
-			goto add_sync_ep;
-		}
+		alts = &iface->altsetting[1];
+		goto add_sync_ep;
 	}
-	if (is_playback &&
-	    attr == USB_ENDPOINT_SYNC_ASYNC &&
+	if (attr == USB_ENDPOINT_SYNC_ASYNC &&
 	    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
 	    altsd->bInterfaceProtocol == 2 &&
 	    altsd->bNumEndpoints == 1 &&
-- 
1.8.1.5

[PATCH v2 8/9] ALSA: usb-audio: remove implicit_fb from quirk

[Eldad Zack]

Since the quirks all apply to implicit feedback (the source endpoint
is always a data endpoint), there's no need to set and check
a flag for it.

Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
---
 sound/usb/pcm.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index af30e08..b375d58 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -334,7 +334,6 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 {
 	struct usb_host_interface *alts;
 	struct usb_interface *iface;
-	int implicit_fb = 0;
 	unsigned int ep;
 
 	/* Implicit feedback sync EPs consumers are always playback EPs */
@@ -344,7 +343,6 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 	switch (subs->stream->chip->usb_id) {
 	case USB_ID(0x0763, 0x2030): /* M-Audio Fast Track C400 */
 	case USB_ID(0x0763, 0x2031): /* M-Audio Fast Track C600 */
-		implicit_fb = 1;
 		ep = 0x81;
 		iface = usb_ifnum_to_if(dev, 3);
 
@@ -356,7 +354,6 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 		break;
 	case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
 	case USB_ID(0x0763, 0x2081):
-		implicit_fb = 1;
 		ep = 0x81;
 		iface = usb_ifnum_to_if(dev, 2);
 
@@ -374,7 +371,6 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 	    search_roland_implicit_fb(dev, altsd->bInterfaceNumber + 1,
 				      altsd->bAlternateSetting,
 				      &alts, &ep) >= 0) {
-		implicit_fb = 1;
 		goto add_sync_ep;
 	}
 
@@ -384,9 +380,7 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 add_sync_ep:
 	subs->sync_endpoint = snd_usb_add_endpoint(subs->stream->chip,
 						   alts, ep, !subs->direction,
-						   implicit_fb ?
-							SND_USB_ENDPOINT_TYPE_DATA :
-							SND_USB_ENDPOINT_TYPE_SYNC);
+						   SND_USB_ENDPOINT_TYPE_DATA);
 	if (!subs->sync_endpoint)
 		return -EINVAL;
 
-- 
1.8.1.5

[PATCH v2 9/9] ALSA: usb-audio: WARN_ON when alts is passed as NULL

[Eldad Zack]

Prevent NULL dereference in snd_usb_add_endpoints(), when
alts is passed as NULL. In this case, WARN (since this is
a non-fatal bug) and return NULL ep. Call sites treat a NULL
return value as an error.

Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
---
 sound/usb/endpoint.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 7a444b5..92ea945 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -418,6 +418,9 @@ struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip,
 	struct snd_usb_endpoint *ep;
 	int is_playback = direction == SNDRV_PCM_STREAM_PLAYBACK;
 
+	if (WARN_ON(!alts))
+		return NULL;
+
 	mutex_lock(&chip->mutex);
 
 	list_for_each_entry(ep, &chip->ep_list, list) {
-- 
1.8.1.5

Re: [PATCH v2 7/9] ALSA: usb-audio: remove is_playback from implicit feedback quirks

[Eldad Zack]

I had some error while sending, and this was sent twice.

On Sat, 3 Aug 2013, Eldad Zack wrote:

> An implicit feedback endpoint can only be a capture source. The
> consumer (sink) of the implicit feedback endpoint is therefore limited
> to playback EPs.
> Check if the target endpoint is a playback first and remove redundant
> checks.
> 
> Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
> ---
>  sound/usb/pcm.c | 40 +++++++++++++++++++---------------------
>  1 file changed, 19 insertions(+), 21 deletions(-)
> 
> diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
> index bb2e0f5..af30e08 100644
> --- a/sound/usb/pcm.c
> +++ b/sound/usb/pcm.c
> @@ -334,41 +334,39 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
>  {
>  	struct usb_host_interface *alts;
>  	struct usb_interface *iface;
> -	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
>  	int implicit_fb = 0;
>  	unsigned int ep;
>  
> +	/* Implicit feedback sync EPs consumers are always playback EPs */
> +	if (subs->direction != SNDRV_PCM_STREAM_PLAYBACK)
> +		return 0;
> +
>  	switch (subs->stream->chip->usb_id) {
>  	case USB_ID(0x0763, 0x2030): /* M-Audio Fast Track C400 */
>  	case USB_ID(0x0763, 0x2031): /* M-Audio Fast Track C600 */
> -		if (is_playback) {
> -			implicit_fb = 1;
> -			ep = 0x81;
> -			iface = usb_ifnum_to_if(dev, 3);
> +		implicit_fb = 1;
> +		ep = 0x81;
> +		iface = usb_ifnum_to_if(dev, 3);
>  
> -			if (!iface || iface->num_altsetting == 0)
> -				return -EINVAL;
> +		if (!iface || iface->num_altsetting == 0)
> +			return -EINVAL;
>  
> -			alts = &iface->altsetting[1];
> -			goto add_sync_ep;
> -		}
> +		alts = &iface->altsetting[1];
> +		goto add_sync_ep;
>  		break;
>  	case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
>  	case USB_ID(0x0763, 0x2081):
> -		if (is_playback) {
> -			implicit_fb = 1;
> -			ep = 0x81;
> -			iface = usb_ifnum_to_if(dev, 2);
> +		implicit_fb = 1;
> +		ep = 0x81;
> +		iface = usb_ifnum_to_if(dev, 2);
>  
> -			if (!iface || iface->num_altsetting == 0)
> -				return -EINVAL;
> +		if (!iface || iface->num_altsetting == 0)
> +			return -EINVAL;
>  
> -			alts = &iface->altsetting[1];
> -			goto add_sync_ep;
> -		}
> +		alts = &iface->altsetting[1];
> +		goto add_sync_ep;
>  	}
> -	if (is_playback &&
> -	    attr == USB_ENDPOINT_SYNC_ASYNC &&
> +	if (attr == USB_ENDPOINT_SYNC_ASYNC &&
>  	    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
>  	    altsd->bInterfaceProtocol == 2 &&
>  	    altsd->bNumEndpoints == 1 &&
> -- 
> 1.8.1.5
>