[BISECTED] 3.17-rc1 radeon screen corruption due to "Always flush the HDP cache before submitting a CS to the GPU"

From: Mikael Pettersson
Date: Sat Aug 30 2014 - 09:59:42 EST

Since 3.17-rc1 my radeon card (RV370 / X1050 card) causes screen corruption
after a while in X + firefox. This still occurs with yesterday's HEAD
of Linus' repo. 3.16 and ealier kernels are fine.

I ran a bisect, which identified:

commit 72a9987edcedb89db988079a03c9b9c65b6ec9ac
Author: Michel Dänzer <michel.daenzer@xxxxxxx>
Date: Thu Jul 31 18:43:49 2014 +0900

drm/radeon: Always flush the HDP cache before submitting a CS to the GPU

as the cause of my screen corruption. Reverting this from 3.17-rc2
(which requires manual intervention due to subsequent changes in
radeon_ring_commit()) eliminates the screen corruption.

User-space is vanilla Fedora 19 / x86_64 with updates. radeon_drv.so says:

[ 62.574] (II) LoadModule: "radeon"
[ 62.574] (II) Loading /usr/lib64/xorg/modules/drivers/radeon_drv.so
[ 62.574] (II) Module radeon: vendor="X.Org Foundation"
[ 62.574] compiled for 1.14.0, module version = 7.1.99
[ 62.574] Module class: X.Org Video Driver
[ 62.574] ABI class: X.Org Video Driver, version 14.1
[ 62.585] (--) RADEON(0): Chipset: "ATI Radeon X550 (RV370) 5B63 (PCIE)" (ChipID = 0x5b63)

See also my original report to LKML:

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/