linux-kernel - Re: Linux-2.6.31-rc4 - shut the annoying "failed to acquire vblank..."

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Date:	Wed, 29 Jul 2009 08:54:02 +0200
From:	Paul Rolland <rol@...917.net>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Frans Pop <elendil@...net.nl>, linux-kernel@...r.kernel.org,
	rol@...be.net
Subject: Re: Linux-2.6.31-rc4 - shut the annoying "failed to acquire
 vblank..."

Hi Linus,

On Tue, 28 Jul 2009 09:23:19 -0700
Jesse Barnes <jbarnes@...tuousgeek.org> wrote:

> On Tue, 28 Jul 2009 14:53:59 +0200
> Paul Rolland <rol@...917.net> wrote:
> 
> > Hi Frans,
> > 
> > On Tue, 28 Jul 2009 12:44:12 +0200
> > Frans Pop <elendil@...net.nl> wrote:
> > 
> > > > I sent a mail long ago about this message :
> > > > tux kernel: [drm:drm_wait_vblank] *ERROR* failed to acquire vblank
> > > > counter, -22 showing up more than 10 times per second, but was
> > > > told that I had some old userspace apps running... As I was using
> > > > an old FC8, I forgot about it.
> > > 
> > > The message does not only show with old applications, it also shows:
> > > - every time I suspend my notebook
> > > - every time I start a second X session to log in as a different
> > > user
> > Well, with the so-called "old apps", it's 20 times per second, as
> > long as the app is running, which really makes it painful, because it
> > causes all the logs to show off quickly :(
> >  
> > > I agree that the message is very annoying and would be glad to be
> > > rid of it, especially as the only comment from the maintainers so
> > > far has been to just ignore it.
> > Well, I'd really like some feedback from the maintainer... because if
> > no one cares, I agree it should be removed.
> > 
> > > IMHO, If it is "ignoreable", then it is also "suppressable".
> > Seconded, unless someone is using it to try to fix the problem ?
> 
> It indicates a userland problem, and yes we shouldn't print that
> message.  I've also posted a patch to quiet it a few times, but Dave
> hasn't picked it up yet.  Feel free to send it straight to Linus with
> my Reviewed-by if you want.

Could you please apply the included patch ?

Some applications/hardware combinations are triggering the message "failed to 
acquire vblank counter" to be issued up to 20 times a second, which makes it 
both useless and dangerous, as this may hide other important messages.
This changes makes it only appear when people are debugging.

Signed-off-by: Paul Rolland <rol@...917.net>
Reviewed-by: Jesse Barnes <jbarnes@...tuousgeek.org>

--- linux-2.6.31-rc4/drivers/gpu/drm/drm_irq.c.orig	2009-07-26 21:36:20.000000000 +0200
+++ linux-2.6.31-rc4/drivers/gpu/drm/drm_irq.c	2009-07-26 21:36:34.000000000 +0200
@@ -566,7 +566,7 @@ int drm_wait_vblank(struct drm_device *d
 
 	ret = drm_vblank_get(dev, crtc);
 	if (ret) {
-		DRM_ERROR("failed to acquire vblank counter, %d\n", ret);
+		DRM_DEBUG("failed to acquire vblank counter, %d\n", ret);
 		return ret;
 	}
 	seq = drm_vblank_count(dev, crtc);



-- 
Paul Rolland                                E-Mail : rol(at)witbe.net
CTO - Witbe.net SA                          Tel. +33 (0)1 47 67 77 77
Les Collines de l'Arche                     Fax. +33 (0)1 47 67 77 99
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View attachment "drm.patch" of type "text/x-patch" (461 bytes)