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; r600_cp_start(rdev); rdev->cp.ready = true; Developer's Certificate of Origin 1.1 By making a contribution to this project, I certify that: (a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or (b) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or (c) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it. (d) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved. Signed-off-by: A R Karthick <a.r.karthick at gmail.com> Reported-by: Mayank Rungta <mr.mynk at gmail.com> Tested-by: Mayank Rungta <mr.mynk at gmail.com>
