[PATCH] ALSA: snd-usb-usx2y: remove bogus frame check

[PATCH] ALSA: snd-usb-usx2y: remove bogus frame check

[Daniel Mack]

The frame check in i_usX2Y_urb_complete() is bogus and produces false
positives as described in this LAU thread:

  http://linuxaudio.org/mailarchive/lau/2013/5/20/200177

This code removes the check code entirely.

Cc: fzu@wemgehoertderstaat.de
Reported-by: Dr Nicholas J Bailey <nicholas.bailey@glasgow.ac.uk>
Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Daniel Mack <zonque@gmail.com>
---
 sound/usb/usx2y/usbusx2yaudio.c | 22 +++-------------------
 1 file changed, 3 insertions(+), 19 deletions(-)

diff --git a/sound/usb/usx2y/usbusx2yaudio.c b/sound/usb/usx2y/usbusx2yaudio.c
index 63fb521..6234a51 100644
--- a/sound/usb/usx2y/usbusx2yaudio.c
+++ b/sound/usb/usx2y/usbusx2yaudio.c
@@ -299,19 +299,6 @@ static void usX2Y_error_urb_status(struct usX2Ydev *usX2Y,
 	usX2Y_clients_stop(usX2Y);
 }
 
-static void usX2Y_error_sequence(struct usX2Ydev *usX2Y,
-				 struct snd_usX2Y_substream *subs, struct urb *urb)
-{
-	snd_printk(KERN_ERR
-"Sequence Error!(hcd_frame=%i ep=%i%s;wait=%i,frame=%i).\n"
-"Most probably some urb of usb-frame %i is still missing.\n"
-"Cause could be too long delays in usb-hcd interrupt handling.\n",
-		   usb_get_current_frame_number(usX2Y->dev),
-		   subs->endpoint, usb_pipein(urb->pipe) ? "in" : "out",
-		   usX2Y->wait_iso_frame, urb->start_frame, usX2Y->wait_iso_frame);
-	usX2Y_clients_stop(usX2Y);
-}
-
 static void i_usX2Y_urb_complete(struct urb *urb)
 {
 	struct snd_usX2Y_substream *subs = urb->context;
@@ -328,12 +315,9 @@ static void i_usX2Y_urb_complete(struct urb *urb)
 		usX2Y_error_urb_status(usX2Y, subs, urb);
 		return;
 	}
-	if (likely((urb->start_frame & 0xFFFF) == (usX2Y->wait_iso_frame & 0xFFFF)))
-		subs->completed_urb = urb;
-	else {
-		usX2Y_error_sequence(usX2Y, subs, urb);
-		return;
-	}
+
+	subs->completed_urb = urb;
+
 	{
 		struct snd_usX2Y_substream *capsubs = usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE],
 			*playbacksubs = usX2Y->subs[SNDRV_PCM_STREAM_PLAYBACK];
-- 
1.8.3.1

Re: [PATCH] ALSA: snd-usb-usx2y: remove bogus frame check

[Takashi Iwai]

At Wed,  2 Oct 2013 15:54:28 +0200,
Daniel Mack wrote:
> 
> The frame check in i_usX2Y_urb_complete() is bogus and produces false
> positives as described in this LAU thread:
> 
>   http://linuxaudio.org/mailarchive/lau/2013/5/20/200177
> 
> This code removes the check code entirely.
> 
> Cc: fzu@wemgehoertderstaat.de
> Reported-by: Dr Nicholas J Bailey <nicholas.bailey@glasgow.ac.uk>
> Suggested-by: Takashi Iwai <tiwai@suse.de>
> Signed-off-by: Daniel Mack <zonque@gmail.com>

It's referred in usx2yhwdeppcm.c, too (the file is included there).

Yeah, I know that the driver code is fairly complex (IOW ugly).  IIRC,
the hwdeppcm mmap is also broken, and we need yet another fix.
Sigh...


thanks,

Takashi

> ---
>  sound/usb/usx2y/usbusx2yaudio.c | 22 +++-------------------
>  1 file changed, 3 insertions(+), 19 deletions(-)
> 
> diff --git a/sound/usb/usx2y/usbusx2yaudio.c b/sound/usb/usx2y/usbusx2yaudio.c
> index 63fb521..6234a51 100644
> --- a/sound/usb/usx2y/usbusx2yaudio.c
> +++ b/sound/usb/usx2y/usbusx2yaudio.c
> @@ -299,19 +299,6 @@ static void usX2Y_error_urb_status(struct usX2Ydev *usX2Y,
>  	usX2Y_clients_stop(usX2Y);
>  }
>  
> -static void usX2Y_error_sequence(struct usX2Ydev *usX2Y,
> -				 struct snd_usX2Y_substream *subs, struct urb *urb)
> -{
> -	snd_printk(KERN_ERR
> -"Sequence Error!(hcd_frame=%i ep=%i%s;wait=%i,frame=%i).\n"
> -"Most probably some urb of usb-frame %i is still missing.\n"
> -"Cause could be too long delays in usb-hcd interrupt handling.\n",
> -		   usb_get_current_frame_number(usX2Y->dev),
> -		   subs->endpoint, usb_pipein(urb->pipe) ? "in" : "out",
> -		   usX2Y->wait_iso_frame, urb->start_frame, usX2Y->wait_iso_frame);
> -	usX2Y_clients_stop(usX2Y);
> -}
> -
>  static void i_usX2Y_urb_complete(struct urb *urb)
>  {
>  	struct snd_usX2Y_substream *subs = urb->context;
> @@ -328,12 +315,9 @@ static void i_usX2Y_urb_complete(struct urb *urb)
>  		usX2Y_error_urb_status(usX2Y, subs, urb);
>  		return;
>  	}
> -	if (likely((urb->start_frame & 0xFFFF) == (usX2Y->wait_iso_frame & 0xFFFF)))
> -		subs->completed_urb = urb;
> -	else {
> -		usX2Y_error_sequence(usX2Y, subs, urb);
> -		return;
> -	}
> +
> +	subs->completed_urb = urb;
> +
>  	{
>  		struct snd_usX2Y_substream *capsubs = usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE],
>  			*playbacksubs = usX2Y->subs[SNDRV_PCM_STREAM_PLAYBACK];
> -- 
> 1.8.3.1
> 

Re: [PATCH] ALSA: snd-usb-usx2y: remove bogus frame check

[Daniel Mack]

On 02.10.2013 17:43, Takashi Iwai wrote:
> At Wed,  2 Oct 2013 15:54:28 +0200,
> Daniel Mack wrote:
>>
>> The frame check in i_usX2Y_urb_complete() is bogus and produces false
>> positives as described in this LAU thread:
>>
>>   http://linuxaudio.org/mailarchive/lau/2013/5/20/200177
>>
>> This code removes the check code entirely.
>>
>> Cc: fzu@wemgehoertderstaat.de
>> Reported-by: Dr Nicholas J Bailey <nicholas.bailey@glasgow.ac.uk>
>> Suggested-by: Takashi Iwai <tiwai@suse.de>
>> Signed-off-by: Daniel Mack <zonque@gmail.com>
> 
> It's referred in usx2yhwdeppcm.c, too (the file is included there).

Eek. I missed that. Thanks for the heads-up.

> Yeah, I know that the driver code is fairly complex (IOW ugly).  IIRC,
> the hwdeppcm mmap is also broken, and we need yet another fix.
> Sigh...

I don't know if Karsten (cc) is still maintaning this piece of code :-/


Daniel