Bug 2573

Summary: Machine lockups with radeon accel
Product: xorg Reporter: Stephane Marchesin <marchesin>
Component: Driver/RadeonAssignee: Xorg Project Team <xorg-team>
Status: RESOLVED FIXED QA Contact:
Severity: major    
Priority: high CC: sroland
Version: git   
Hardware: x86 (IA32)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
Proposed patch none

Description Stephane Marchesin 2005-02-18 07:35:20 UTC 
Using Xorg CVS on my radeon 7000 (1002:5159), the machine lockups (no ping, no
sysrq) when Mozilla scrolls. Using another card with the same PCI id,
(1002:5159) on another machine, the problem doesn't happen. So there is really
no way to tell if the card has this problem (IIRC, the difference between the
cards is a card setting that's done in the video bios).

If I comment the cache flush turn off that happens in radeon_accel.c (thanks to
Roland for the hint), the problem disappears and I can happily scroll in
mozilla. It seems that this cache setting was already causing trouble for
R300-style cards, so I propose removing it for all cards.
Comment 1 Stephane Marchesin 2005-02-18 07:36:10 UTC 
Created attachment 1934 [details] [review]
Proposed patch
Comment 2 Roland Scheidegger 2005-09-14 09:56:10 UTC 
Raising severity, as more or less unpredictable lockups on some unknown cards
really is a problem (there are, btw, quite some bugs about strange lockups
associated with radeons in the database, which might or might not be related).
I tried to figure out why automatic flushing was turned off in the first place,
I can't see a reason. Some 2d and 3d performance tests (x11perf -scroll100 and
others, quake3) showed up absolutely no difference whatsoever with it enabled or
disabled (on a rv250). The code in Xorg / Xfree always had that setting (the
original checkin seemed to be here:
http://cvsweb.xfree86.org/cvsweb/xc/programs/Xserver/hw/xfree86/drivers/r128/Attic/)
So, why I don't know why disabling automatic flushing would cause lockups in the
first place, I'd suggest that setting to be removed, unless some cards are known
to lockup when it's NOT disabled (original R100 is probably the only card this
is even a possibility?). Maybe someone from ATI could comment if this is indeed
necessary for some cards?
Comment 3 Eric Anholt 2005-09-14 15:08:13 UTC 
I think I've implicated these lines in bad rendering myself, so I went ahead and
committed.  Let's not make our code questionable for some unmeasured theoretical
performance gain (the only question I had was whether disabling this might hide
wrong flushing policy on my part, but I can't find any for the life of me).

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