linux-kernel - Re: [radeon r100] when ring test fails, provide users with option to test

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Message-ID: <20151201100110.GE21222@amd>
Date:	Tue, 1 Dec 2015 11:01:10 +0100
From:	Pavel Machek <pavel@....cz>
To:	Christian König <christian.koenig@....com>
Cc:	Trivial patch monkey <trivial@...nel.org>,
	alexander.deucher@....com, airlied@...ux.ie,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [radeon r100] when ring test fails, provide users with option to
 test

On Mon 2015-11-30 09:39:54, Christian König wrote:
> On 29.11.2015 23:22, Pavel Machek wrote:
> >On Sun 2015-11-29 20:48:53, Christian König wrote:
> >>On 28.11.2015 21:58, Pavel Machek wrote:
> >>>Ring test failure is often caused by too high agpmode. Tell the user
> >>>what to try.
> >>>
> >>>Signed-off-by: Pavel Machek <pavel@....cz>
> >>NAK, the ring test can fail for any number of reasons and the agpmode is
> >>actually rather unlikely to be the cause.
> >Well, when I asked on the list "why this is happened" I got "umm,
> >noone knows" response that was not exactly helpful. And then someone
> >told me about agpmode.
> >
> >If you know about the reasons it can fail, could you list them near
> >the DRM_ERROR, at least as a comment?
> 
> Well as I said, that could be any number of reasons. Some of them even
> completely unrelated to the driver itself.
> 
> E.g. BIOS setting, faulty hardware, problems with the writeback etc... There
> is really not a list you could give here.
> 
> Lowering the agpmode usually helps more to prevent random corruptions and
> problems under load.

Take a look at

http://www.gossamer-threads.com/lists/linux/kernel/2197183

. I had a problem, you did not know how to debug it, but it already
happened to pebolle at tiscali ... and yes, it was agpmode. That
problem is clearly more common then you realize... So this should go
in.

									Pavel

> >>>--- a/drivers/gpu/drm/radeon/r100.c
> >>>+++ b/drivers/gpu/drm/radeon/r100.c
> >>>@@ -3665,7 +3665,7 @@ int r100_ring_test(struct radeon_device *rdev, struct radeon_ring *ring)
> >>>  	if (i < rdev->usec_timeout) {
> >>>  		DRM_INFO("ring test succeeded in %d usecs\n", i);
> >>>  	} else {
> >>>-		DRM_ERROR("radeon: ring test failed (scratch(0x%04X)=0x%08X)\n",
> >>>+		DRM_ERROR("radeon: ring test failed (scratch(0x%04X)=0x%08X), try radeon.agpmode=1?\n",
> >>>  			  scratch, tmp);
> >>>  		r = -EINVAL;
> >>>  	}
> >>>

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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