Module Name: src Committed By: riastradh Date: Wed Feb 25 13:35:25 UTC 2015
Modified Files: src/sys/external/bsd/drm2/dist/drm/i915: intel_ringbuffer.c Log Message: Back-port attempt [2/2] to fix i915drmkms on G4X, from Linux. commit 95468892fdfeef6d1004b524e35957629efdbe00 Author: Chris Wilson <ch...@chris-wilson.co.uk> Date: Thu Aug 7 15:39:54 2014 +0100 drm/i915: Reset the HEAD pointer for the ring after writing START Ville found an old w/a documented for g4x that suggested that we need to reset the HEAD after writing START. This is a useful fixup for some of the g4x ring initialisation woes, but as usual, not all. v2: Do the rewrite unconditionally anyway To generate a diff of this commit: cvs rdiff -u -r1.5 -r1.6 \ src/sys/external/bsd/drm2/dist/drm/i915/intel_ringbuffer.c Please note that diffs are not public domain; they are subject to the copyright notices on the relevant files.
Modified files: Index: src/sys/external/bsd/drm2/dist/drm/i915/intel_ringbuffer.c diff -u src/sys/external/bsd/drm2/dist/drm/i915/intel_ringbuffer.c:1.5 src/sys/external/bsd/drm2/dist/drm/i915/intel_ringbuffer.c:1.6 --- src/sys/external/bsd/drm2/dist/drm/i915/intel_ringbuffer.c:1.5 Wed Feb 25 13:30:02 2015 +++ src/sys/external/bsd/drm2/dist/drm/i915/intel_ringbuffer.c Wed Feb 25 13:35:25 2015 @@ -507,6 +507,14 @@ static int init_ring_common(struct intel * also enforces ordering), otherwise the hw might lose the new ring * register values. */ I915_WRITE_START(ring, i915_gem_obj_ggtt_offset(obj)); + + /* WaClearRingBufHeadRegAtInit:ctg,elk */ + if (I915_READ_HEAD(ring)) + DRM_DEBUG("%s initialization failed [head=%08x], fudging\n", + ring->name, I915_READ_HEAD(ring)); + I915_WRITE_HEAD(ring, 0); + (void)I915_READ_HEAD(ring); + I915_WRITE_CTL(ring, ((ring->size - PAGE_SIZE) & RING_NR_PAGES) | RING_VALID);