On 6/26/2024 9:13 PM, Imre Deak wrote:
Atm the link on DP-SST is retrained without a full modeset, which
probably causes an underrun. This was originally done for simplicity,
the underrun not causing further known issues. The plan is to retrain
the link with a full modeset instead on DP-SST as well, similarly to how
this is done on DP-MST already:
https://github.com/ideak/linux/commits/sst-modeset-retrain
Thanks Imre, I validated with the given patches from link above, we are
not seeing the underruns with these.
We can drop my patch and perhaps you can float your changes for review.
Regards,
Ankit
On Wed, Jun 26, 2024 at 03:18:32PM +0000, Runyan, Arthur J wrote:
There is no underrun expected (that I know of) when coming out of
training on recent product generations. You should undo this masking
and debug.
-----Original Message-----
From: Vivi, Rodrigo <rodrigo.vivi@xxxxxxxxx>
Sent: Wednesday, June 26, 2024 8:13 AM
To: Nautiyal, Ankit K <ankit.k.nautiyal@xxxxxxxxx>; Runyan, Arthur J <arthur.j.runyan@xxxxxxxxx>
Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; intel-xe@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [PATCH] drm/i915/dp: Wait more before rearming FIFO underrun during retrain
On Wed, Jun 26, 2024 at 02:06:24PM +0530, Ankit Nautiyal wrote:
During Link re-training reporting underrun is disabled and then
renabled after re-training is completed. For BMG its seen that we get
FIFO underrun just after the retraining is completed and the underrun
reporting is re-enabled.
Add one more intel_crtc_wait_for_next_vblank before re-arming the
underruns.
Cc: Arthur Runyan <arthur.j.runyan@xxxxxxxxx>
Art, any new workaround in BMG for this issue?
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dp.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index 3903f6ead6e6..25af51499383 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5325,7 +5325,12 @@ static int intel_dp_retrain_link(struct intel_encoder *encoder,
const struct intel_crtc_state *crtc_state =
to_intel_crtc_state(crtc->base.state);
- /* Keep underrun reporting disabled until things are stable */
+ /*
+ * Keep underrun reporting disabled until things are stable.
+ * Wait for some more time, as we see (at least on BMG) that
+ * underrun gets reported just after the reporting is enabled.
+ */
+ intel_crtc_wait_for_next_vblank(crtc);
intel_crtc_wait_for_next_vblank(crtc);
intel_set_cpu_fifo_underrun_reporting(dev_priv, crtc->pipe, true);
--
2.40.1
