On Mit, 2011-08-10 at 09:27 -0400, Alex Deucher wrote: > 2011/8/10 Michel D?nzer <michel at daenzer.net>: > > 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 - > >> > >> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/820746/ > >> > >> --- > >> > >> BUG: unable to handle kernel paging request at fa501ffc - Oops at > >> r600_cp_start+0x48/0x380 in r600_cp_resume+0x345/0x580 [radeon] > >> > >> drivers/gpu/drm/radeon/r600.c > >> > >> > >> > >> --- 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; > > > > 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 > > think? > > Either this or reset the registers to 0 or a saved value on resume > rather than reading from them.
The patch below is what I had in mind. Does this fix the problem above?
