This is a note to let you know that I've just added the patch titled
drm/amd/display: only accept async flips for fast updates
to the 6.4-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-amd-display-only-accept-async-flips-for-fast-updates.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1ca67aba8d11c2849d395013e1fdce02918d5657 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@xxxxxxxxxxx>
Date: Wed, 21 Jun 2023 17:24:59 -0300
Subject: drm/amd/display: only accept async flips for fast updates
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Simon Ser <contact@xxxxxxxxxxx>
commit 1ca67aba8d11c2849d395013e1fdce02918d5657 upstream.
Up until now, amdgpu was silently degrading to vsync when
user-space requested an async flip but the hardware didn't support
it.
The hardware doesn't support immediate flips when the update changes
the FB pitch, the DCC state, the rotation, enables or disables CRTCs
or planes, etc. This is reflected in the dm_crtc_state.update_type
field: UPDATE_TYPE_FAST means that immediate flip is supported.
Silently degrading async flips to vsync is not the expected behavior
from a uAPI point-of-view. Xorg expects async flips to fail if
unsupported, to be able to fall back to a blit. i915 already behaves
this way.
This patch aligns amdgpu with uAPI expectations and returns a failure
when an async flip is not possible.
Signed-off-by: Simon Ser <contact@xxxxxxxxxxx>
Reviewed-by: André Almeida <andrealmeid@xxxxxxxxxx>
Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>
Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 8 ++++++++
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c | 12 ++++++++++++
2 files changed, 20 insertions(+)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -8055,7 +8055,15 @@ static void amdgpu_dm_commit_planes(stru
* Only allow immediate flips for fast updates that don't
* change memory domain, FB pitch, DCC state, rotation or
* mirroring.
+ *
+ * dm_crtc_helper_atomic_check() only accepts async flips with
+ * fast updates.
*/
+ if (crtc->state->async_flip &&
+ acrtc_state->update_type != UPDATE_TYPE_FAST)
+ drm_warn_once(state->dev,
+ "[PLANE:%d:%s] async flip with non-fast update\n",
+ plane->base.id, plane->name);
bundle->flip_addrs[planes_count].flip_immediate =
crtc->state->async_flip &&
acrtc_state->update_type == UPDATE_TYPE_FAST &&
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
@@ -398,6 +398,18 @@ static int dm_crtc_helper_atomic_check(s
return -EINVAL;
}
+ /*
+ * Only allow async flips for fast updates that don't change the FB
+ * pitch, the DCC state, rotation, etc.
+ */
+ if (crtc_state->async_flip &&
+ dm_crtc_state->update_type != UPDATE_TYPE_FAST) {
+ drm_dbg_atomic(crtc->dev,
+ "[CRTC:%d:%s] async flips are only supported for fast updates\n",
+ crtc->base.id, crtc->name);
+ return -EINVAL;
+ }
+
/* In some use cases, like reset, no stream is attached */
if (!dm_crtc_state->stream)
return 0;
Patches currently in stable-queue which might be from contact@xxxxxxxxxxx are
queue-6.4/drm-amd-display-only-accept-async-flips-for-fast-updates.patch
