Re: [PATCH 2.6.38-10-generic] device driver: fix oops in radeondriver due to incorrect value from hardware
From: Michel Dänzer
Date: Wed Aug 10 2011 - 05:33:03 EST
On Die, 2011-08-09 at 23:52 +0530, Mayank Rungta wrote:
> Added a check for the radeon ring buffer write index in r600.c which
> reads 0xffffffff on resume. This results in an Oops during
> radeon_ring_write. Masking the value averts this.
> This problem is not seen to be fixed in 3.0 r600.c as well.
> Detailed analysis of the problem can be found at -
> BUG: unable to handle kernel paging request at fa501ffc - Oops at
> r600_cp_start+0x48/0x380 in r600_cp_resume+0x345/0x580 [radeon]
> --- linux-2.6.38/drivers/gpu/drm/radeon/r600.c.orig 2011-08-05
> 15:39:40.824612700 +0530
> +++ linux-2.6.38/drivers/gpu/drm/radeon/r600.c 2011-08-08
> 05:29:21.744417857 +0530
> @@ -2218,6 +2218,8 @@ int r600_cp_resume(struct radeon_device
> rdev->cp.rptr = RREG32(CP_RB_RPTR);
> rdev->cp.wptr = RREG32(CP_RB_WPTR);
> + /* protect against crazy HW on resume */
> + rdev->cp.wptr &= rdev->cp.ptr_mask;
The indentation of the lines you're adding doesn't match the surrounding
Although the same workaround is already in r100.c, I wonder if we
shouldn't rather try and eliminate all reads from the CP_RB_WPTR
register, at least other than for debugging purposes. Alex, what do you
Otherwise, this should probably be added in evergreen.c as well.
> Developer's Certificate of Origin 1.1
No need to include all this text, just the *-by: tags are enough.
Earthling Michel DÃnzer | http://www.amd.com
Libre software enthusiast | Debian, X and DRI developer
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