linux-kernel - Re: [Linux-fbdev-devel] radeonfb lockup in .28-rc (bisected)

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Date:	Mon, 03 Nov 2008 10:33:04 -0500
From:	James Cloos <cloos@...loos.com>
To:	benh@...nel.crashing.org
Cc:	linux-fbdev-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Krzysztof Halasa <khc@...waw.pl>
Subject: Re: [Linux-fbdev-devel] radeonfb lockup in .28-rc (bisected)

>>>>> "Benjamin" == Benjamin Herrenschmidt <benh@...nel.crashing.org> writes:

>> is in play.  It is probably spinning through all of the 2000000 possible
>> udelay(10) calls.  I don't think I ever gave it twenty seconds before
>> giving up.  And certainly not forty seconds, if the freeze happens after
>> setting the DST_Y_X register.

Benjamin> Well, setting DST_Y_X is what triggers the transfer. The above
Benjamin> means that the FIFO isn't emptying (ie, the engine is locked up).

I gave it another try over the weekend and let it sit for five minutes.
The reset message never appeared.

Benjamin>  - We can blacklist that chip for imageblit (it's not a huge
Benjamin> improvement on x86 anyway).

No objections here.

Benjamin>  - We can be smart, reduce the timeout above, and "detect" the
Benjamin> lockup, when it happens, reset the engine and disable the
Benjamin> acceleration that locked up.

Given Paul's report, that seems like the long term solution.

Benjamin> Now, the problem is ... My second son was just born last
Benjamin> wed. so I'm pretty unavailable right now.

Congrats!

Benjamin>  Thus, for .29, I'm tempted to go for the simpler approach
Benjamin> which is to blacklist M7's from imageblit acceleration.

Again, that is fine by me.  Otherwise I'll just leave the #if0 commit
in my compile clone.

-JimC
-- 
James Cloos <cloos@...loos.com>         OpenPGP: 1024D/ED7DAEA6
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