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drm/i915: Declare the swizzling unknown for L-shaped configurations

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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@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Chris Wilson 2015-06-29 14:01:19 +01:00 committed by Daniel Vetter
parent dec4f799d0
commit 19ee835cdb
1 changed files with 11 additions and 1 deletions
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12
drivers/gpu/drm/i915/i915_gem_tiling.c
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@ -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) {