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

From: Christian KÃnig
Date: Wed Dec 02 2015 - 03:57:38 EST


On 02.12.2015 04:14, Michel DÃnzer wrote:
On 01.12.2015 19:01, Pavel Machek wrote:
On Mon 2015-11-30 09:39:54, Christian KÃnig wrote:
On 29.11.2015 23:22, Pavel Machek wrote:
On Sun 2015-11-29 20:48:53, Christian KÃnig 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@xxxxxx>
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.
I agree with Christian, but at the very least, agpmode must not be
mentioned if AGP isn't being used in the first place, i.e. either the
GPU isn't AGP or is being forced to PCI(e) mode.

Well maybe to explain the background, r100_ring_test() is used for a whole bunch of different hardware generations.

Most of them doesn't even have AGP, so mentioning this here would be even confusion for the majority of users.

Regards,
Christian.
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