This is a note to let you know that I've just added the patch titled
drm/i915: Don't use BAR mappings for ring buffers with LLC
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-i915-don-t-use-bar-mappings-for-ring-buffers-with-llc.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 85636167e3206c3fbd52254fc432991cc4e90194 Mon Sep 17 00:00:00 2001
From: John Harrison <[email protected]>
Date: Wed, 15 Feb 2023 17:11:01 -0800
Subject: drm/i915: Don't use BAR mappings for ring buffers with LLC
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From: John Harrison <[email protected]>
commit 85636167e3206c3fbd52254fc432991cc4e90194 upstream.
Direction from hardware is that ring buffers should never be mapped
via the BAR on systems with LLC. There are too many caching pitfalls
due to the way BAR accesses are routed. So it is safest to just not
use it.
Signed-off-by: John Harrison <[email protected]>
Fixes: 9d80841ea4c9 ("drm/i915: Allow ringbuffers to be bound anywhere")
Cc: Chris Wilson <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: [email protected]
Cc: <[email protected]> # v4.9+
Tested-by: Jouni Högander <[email protected]>
Reviewed-by: Daniele Ceraolo Spurio <[email protected]>
Link:
https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 65c08339db1ada87afd6cfe7db8e60bb4851d919)
Signed-off-by: Jani Nikula <[email protected]>
Signed-off-by: John Harrison <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/gpu/drm/i915/gt/intel_ringbuffer.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
@@ -1208,7 +1208,7 @@ int intel_ring_pin(struct intel_ring *ri
if (unlikely(ret))
goto err_unpin;
- if (i915_vma_is_map_and_fenceable(vma))
+ if (i915_vma_is_map_and_fenceable(vma) && !HAS_LLC(vma->vm->i915))
addr = (void __force *)i915_vma_pin_iomap(vma);
else
addr = i915_gem_object_pin_map(vma->obj,
@@ -1252,7 +1252,7 @@ void intel_ring_unpin(struct intel_ring
intel_ring_reset(ring, ring->emit);
i915_vma_unset_ggtt_write(vma);
- if (i915_vma_is_map_and_fenceable(vma))
+ if (i915_vma_is_map_and_fenceable(vma) && !HAS_LLC(vma->vm->i915))
i915_vma_unpin_iomap(vma);
else
i915_gem_object_unpin_map(vma->obj);
Patches currently in stable-queue which might be from [email protected]
are
queue-5.4/drm-i915-don-t-use-bar-mappings-for-ring-buffers-with-llc.patch
