This is a note to let you know that I've just added the patch titled
drm/i915/dsb: Fix DSB vblank waits when using VRR
to the 6.8-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-dsb-fix-dsb-vblank-waits-when-using-vrr.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f12751168f1a49ebb84b8056cf038973c53b284f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@xxxxxxxxxxxxxxx>
Date: Wed, 6 Mar 2024 06:08:05 +0200
Subject: drm/i915/dsb: Fix DSB vblank waits when using VRR
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From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
commit f12751168f1a49ebb84b8056cf038973c53b284f upstream.
Looks like the undelayed vblank gets signalled exactly when
the active period ends. That is a problem for DSB+VRR when
we are already in vblank and expect DSB to start executing
as soon as we send the push. Instead of starting, the DSB
just keeps on waiting for the undelayed vblank which won't
signal until the end of the next frame's active period,
which is far too late.
The end result is that DSB won't have even started
executing by the time the flips/etc. have completed.
We then wait for an extra 1ms, after which we terminate
the DSB and report a timeout:
[drm] *ERROR* [CRTC:80:pipe A] DSB 0 timed out waiting for idle (current head=0xfedf4000, head=0x0, tail=0x1080)
To fix this let's configure DSB to use the so called VRR
"safe window" instead of the undelayed vblank to trigger
the DSB vblank logic, when VRR is enabled.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 34d8311f4a1c ("drm/i915/dsb: Re-instate DSB for LUT updates")
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9927
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240306040806.21697-3-ville.syrjala@xxxxxxxxxxxxxxx
Reviewed-by: Animesh Manna <animesh.manna@xxxxxxxxx>
(cherry picked from commit 41429d9b68367596eb3d6d5961e6295c284622a7)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dsb.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -340,6 +340,17 @@ static int intel_dsb_dewake_scanline(con
return max(0, vblank_start - intel_usecs_to_scanlines(adjusted_mode, latency));
}
+static u32 dsb_chicken(struct intel_crtc *crtc)
+{
+ if (crtc->mode_flags & I915_MODE_FLAG_VRR)
+ return DSB_CTRL_WAIT_SAFE_WINDOW |
+ DSB_CTRL_NO_WAIT_VBLANK |
+ DSB_INST_WAIT_SAFE_WINDOW |
+ DSB_INST_NO_WAIT_VBLANK;
+ else
+ return 0;
+}
+
static void _intel_dsb_commit(struct intel_dsb *dsb, u32 ctrl,
int dewake_scanline)
{
@@ -361,6 +372,9 @@ static void _intel_dsb_commit(struct int
intel_de_write_fw(dev_priv, DSB_CTRL(pipe, dsb->id),
ctrl | DSB_ENABLE);
+ intel_de_write_fw(dev_priv, DSB_CHICKEN(pipe, dsb->id),
+ dsb_chicken(crtc));
+
intel_de_write_fw(dev_priv, DSB_HEAD(pipe, dsb->id),
intel_dsb_buffer_ggtt_offset(&dsb->dsb_buf));
Patches currently in stable-queue which might be from ville.syrjala@xxxxxxxxxxxxxxx are
queue-6.8/drm-i915-try-to-preserve-the-current-shared_dpll-for-fastset-on-type-c-ports.patch
queue-6.8/drm-i915-pre-populate-the-cursor-physical-dma-address.patch
queue-6.8/drm-i915-replace-a-memset-with-zero-initialization.patch
queue-6.8/drm-i915-add-missing-to-__assign_str-macros-in-trace.patch
queue-6.8/drm-i915-dsi-go-back-to-the-previous-init_otp-display_on-order-mostly.patch
queue-6.8/drm-i915-bios-tolerate-devdata-null-in-intel_bios_encoder_supports_dp_dual_mode.patch
queue-6.8/drm-i915-include-the-pll-name-in-the-debug-messages.patch
queue-6.8/drm-i915-suppress-old-pll-pipe_mask-checks-for-mg-tc-tbt-plls.patch
queue-6.8/drm-i915-dsb-fix-dsb-vblank-waits-when-using-vrr.patch
queue-6.8/drm-i915-vrr-generate-vrr-safe-window-for-dsb.patch
