diff options
| author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2012-02-02 09:58:12 +0100 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2012-02-08 23:16:24 +0100 |
| commit | f691e2f4cec334e906f971471b3bf1460c6256d4 (patch) | |
| tree | 1397e4e39cc1322b3458365e8b10aeca71f8383f /drivers/gpu/drm/i915/i915_gem_tiling.c | |
| parent | 172975aa746e155533cb386c7159c2d6510e2bc8 (diff) | |
drm/i915: swizzling support for snb/ivb
We have to do this manually. Somebody had a Great Idea.
I've measured speed-ups just a few percent above the noise level
(below 5% for the best case), but no slowdows. Chris Wilson measured
quite a bit more (10-20% above the usual snb variance) on a more
recent and better tuned version of sna, but also recorded a few
slow-downs on benchmarks know for uglier amounts of snb-induced
variance.
v2: Incorporate Ben Widawsky's preliminary review comments and
elaborate a bit about the performance impact in the changelog.
v3: Add a comment as to why we don't need to check the 3rd memory
channel.
v4: Fixup whitespace.
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'drivers/gpu/drm/i915/i915_gem_tiling.c')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gem_tiling.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c index 861223bf3944..1a9306665987 100644 --- a/drivers/gpu/drm/i915/i915_gem_tiling.c +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c @@ -93,8 +93,23 @@ i915_gem_detect_bit_6_swizzle(struct drm_device *dev) uint32_t swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN; if (INTEL_INFO(dev)->gen >= 6) { - swizzle_x = I915_BIT_6_SWIZZLE_NONE; - swizzle_y = I915_BIT_6_SWIZZLE_NONE; + uint32_t dimm_c0, dimm_c1; + dimm_c0 = I915_READ(MAD_DIMM_C0); + dimm_c1 = I915_READ(MAD_DIMM_C1); + dimm_c0 &= MAD_DIMM_A_SIZE_MASK | MAD_DIMM_B_SIZE_MASK; + dimm_c1 &= MAD_DIMM_A_SIZE_MASK | MAD_DIMM_B_SIZE_MASK; + /* Enable swizzling when the channels are populated with + * identically sized dimms. We don't need to check the 3rd + * channel because no cpu with gpu attached ships in that + * configuration. Also, swizzling only makes sense for 2 + * channels anyway. */ + if (dimm_c0 == dimm_c1) { + swizzle_x = I915_BIT_6_SWIZZLE_9_10; + swizzle_y = I915_BIT_6_SWIZZLE_9; + } else { + swizzle_x = I915_BIT_6_SWIZZLE_NONE; + swizzle_y = I915_BIT_6_SWIZZLE_NONE; + } } else if (IS_GEN5(dev)) { /* On Ironlake whatever DRAM config, GPU always do * same swizzling setup. |