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drm/i915/clflush: disallow on discrete

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We seem to have an unfortunate issue where we arrive from:

    i915_gem_object_flush_if_display+0x86/0xd0 [i915]
    intel_user_framebuffer_dirty+0x1a/0x50 [i915]
    drm_mode_dirtyfb_ioctl+0xfb/0x1b0

which can be before the pages are populated(and pinned for display), and
so i915_gem_object_has_struct_page() might still return true, as per the
ttm backend. We could re-order the later get_pages() call here, but
since on discrete everything should already be coherent, with the
exception of the display engine, and even there display surfaces must be
allocated in device local-memory anyway, so there should in theory be no
conceivable reason to ever call i915_gem_clflush_object() on discrete.

References: https://gitlab.freedesktop.org/drm/intel/-/issues/4320
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211027161813.3094681-2-matthew.auld@intel.com
This commit is contained in:
Matthew Auld 2021-10-27 17:18:11 +01:00
parent 3ea355b234
commit c52b3b4897
1 changed files with 3 additions and 2 deletions
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5
drivers/gpu/drm/i915/gem/i915_gem_clflush.c
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@ -69,6 +69,7 @@ static struct clflush *clflush_work_create(struct drm_i915_gem_object *obj)
bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
unsigned int flags)
{
struct drm_i915_private *i915 = to_i915(obj->base.dev);
struct clflush *clflush;
assert_object_held(obj);
@ -80,7 +81,7 @@ bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
* anything not backed by physical memory we consider to be always
* coherent and not need clflushing.
*/
if (!i915_gem_object_has_struct_page(obj)) {
if (!i915_gem_object_has_struct_page(obj) || IS_DGFX(i915)) {
obj->cache_dirty = false;
return false;
}
@ -105,7 +106,7 @@ bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
if (clflush) {
i915_sw_fence_await_reservation(&clflush->base.chain,
obj->base.resv, NULL, true,
i915_fence_timeout(to_i915(obj->base.dev)),
i915_fence_timeout(i915),
I915_FENCE_GFP);
dma_resv_add_excl_fence(obj->base.resv, &clflush->base.dma);
dma_fence_work_commit(&clflush->base);