Commit 5bc1d6f6 authored by Chris Wilson's avatar Chris Wilson Committed by Kamal Mostafa

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

commit 5eb3e5a5 upstream.

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.

Note that this is a new attempt for the previously merged one,
reverted in

commit d82c0ba6
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Tue Jul 14 12:29:27 2015 +0200

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

This is cc: stable since we need it to fix up troubles with wc cpu
mmaps that userspace recently started to use widely.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91105Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
[danvet: Add note about previous (failed attempt).]
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
parent 967ba99b
...@@ -464,7 +464,10 @@ i915_gem_get_tiling(struct drm_device *dev, void *data, ...@@ -464,7 +464,10 @@ i915_gem_get_tiling(struct drm_device *dev, void *data,
} }
/* Hide bit 17 from the user -- see comment in i915_gem_set_tiling */ /* Hide bit 17 from the user -- see comment in i915_gem_set_tiling */
args->phys_swizzle_mode = args->swizzle_mode; if (dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES)
args->phys_swizzle_mode = I915_BIT_6_SWIZZLE_UNKNOWN;
else
args->phys_swizzle_mode = args->swizzle_mode;
if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17) if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17)
args->swizzle_mode = I915_BIT_6_SWIZZLE_9; args->swizzle_mode = I915_BIT_6_SWIZZLE_9;
if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17) if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
......
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