The old style of memory interleaving swizzled upto the end of the first even bank of memory, and then used the remainder as unswizzled on the unpaired bank - i.e. swizzling is not constant for all memory. This causes problems when we try to migrate memory and so the kernel prevents migration at all when we detect L-shaped inconsistent swizzling. However, this issue also extends to userspace who try to manually detile into memory as the swizzling for an individual page is unknown (it depends on its physical address only known to the kernel), userspace cannot correctly swizzle objects. v2: Mark the global swizzling as unknown rather than adjust the value reported to userspace. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91105 Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx --- drivers/gpu/drm/i915/i915_gem_tiling.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c index d16585f788ea..a0d98f0abc71 100644 --- a/drivers/gpu/drm/i915/i915_gem_tiling.c +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c @@ -183,8 +183,18 @@ i915_gem_detect_bit_6_swizzle(struct drm_device *dev) if (IS_GEN4(dev)) { uint32_t ddc2 = I915_READ(DCC2); - if (!(ddc2 & DCC2_MODIFIED_ENHANCED_DISABLE)) + if (!(ddc2 & DCC2_MODIFIED_ENHANCED_DISABLE)) { + /* Since the swizzling may vary within an + * object, we have no idea what the swizzling + * is for any page in particular. Thus we + * cannot migrate tiled pages using the GPU, + * nor can we tell userspace what the exact + * swizzling is for any object. + */ dev_priv->quirks |= QUIRK_PIN_SWIZZLED_PAGES; + swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN; + swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN; + } } if (dcc == 0xffffffff) { -- 2.1.4 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
