Re: 6.10/bisected/regression - commits bc87d666c05 and 6d4279cb99ac cause appearing green flashing bar on top of screen on Radeon 6900XT and 120Hz
From: Alex Deucher
Date: Fri Jun 07 2024 - 09:40:03 EST
On Sun, May 26, 2024 at 10:12 AM Mikhail Gavrilov
<mikhail.v.gavrilov@xxxxxxxxx> wrote:
>
> Hi,
> Day before yesterday I replaced 7900XTX to 6900XT for got clear in
> which kernel first time appeared warning message "DMA-API: amdgpu
> 0000:0f:00.0: cacheline tracking EEXIST, overlapping mappings aren't
> supported".
> The kernel 6.3 and older won't boot on a computer with Radeon 7900XTX.
> When I booted the system with 6900XT I saw a green flashing bar on top
> of the screen when I typed commands in the gnome terminal which was
> maximized on full screen.
> Demonstration: https://youtu.be/tTvwQ_5pRkk
> For reproduction you need Radeon 6900XT GPU connected to 120Hz OLED TV by HDMI.
>
> I bisected the issue and the first commit which I found was 6d4279cb99ac.
> commit 6d4279cb99ac4f51d10409501d29969f687ac8dc (HEAD)
> Author: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
> Date: Tue Mar 26 10:42:05 2024 -0600
>
> drm/amd/display: Drop legacy code
>
> This commit removes code that are not used by display anymore.
>
> Acked-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
>
> drivers/gpu/drm/amd/display/dc/inc/hw/stream_encoder.h | 4 ----
> drivers/gpu/drm/amd/display/dc/inc/resource.h | 7 -------
> drivers/gpu/drm/amd/display/dc/optc/dcn20/dcn20_optc.c | 10 ----------
> drivers/gpu/drm/amd/display/dc/resource/dcn21/dcn21_resource.c | 33
> +--------------------------------
> 4 files changed, 1 insertion(+), 53 deletions(-)
>
> Every time after bisecting I usually make sure that I found the right
> commit and build the kernel with revert of the bad commit.
> But this time I again observed an issue after running a kernel builded
> without commit 6d4279cb99ac.
> And I decided to find a second bad commit.
> The second bad commit has been bc87d666c05.
> commit bc87d666c05a13e6d4ae1ddce41fc43d2567b9a2 (HEAD)
> Author: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
> Date: Tue Mar 26 11:55:19 2024 -0600
>
> drm/amd/display: Add fallback configuration for set DRR in DCN10
>
> Set OTG/OPTC parameters to 0 if something goes wrong on DCN10.
>
> Acked-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
>
> drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> After reverting both these commits on top of 54f71b0369c9 the issue is gone.
>
> I also attach the build config.
>
> My hardware specs: https://linux-hardware.org/?probe=f25a873c5e
>
> Rodrigo or anyone else from the AMD team can you look please.
@Siqueira, Rodrigo can you take a look? The two patches change the
programming of OTG_V_TOTAL_CONTROL. The first patch removes this
code:
diff --git a/drivers/gpu/drm/amd/display/dc/optc/dcn20/dcn20_optc.c
b/drivers/gpu/drm/amd/display/dc/optc/dcn20/dcn20_optc.c
index 58bdbd859bf9..d6f095b4555d 100644
--- a/drivers/gpu/drm/amd/display/dc/optc/dcn20/dcn20_optc.c
+++ b/drivers/gpu/drm/amd/display/dc/optc/dcn20/dcn20_optc.c
@@ -462,16 +462,6 @@ void optc2_setup_manual_trigger(struct
timing_generator *optc)
{
struct optc *optc1 = DCN10TG_FROM_TG(optc);
- /* Set the min/max selectors unconditionally so that
- * DMCUB fw may change OTG timings when necessary
- * TODO: Remove the w/a after fixing the issue in DMCUB firmware
- */
- REG_UPDATE_4(OTG_V_TOTAL_CONTROL,
- OTG_V_TOTAL_MIN_SEL, 1,
- OTG_V_TOTAL_MAX_SEL, 1,
- OTG_FORCE_LOCK_ON_EVENT, 0,
- OTG_SET_V_TOTAL_MIN_MASK, (1 << 1));
/* TRIGA */
-
REG_SET_8(OTG_TRIGA_CNTL, 0,
OTG_TRIGA_SOURCE_SELECT, 21,
OTG_TRIGA_SOURCE_PIPE_SELECT, optc->inst,
and the second patch adds this hunk:
diff --git a/drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c
b/drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c
index f109a101d84f..5574bc628053 100644
--- a/drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c
+++ b/drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c
@@ -945,10 +945,19 @@ void optc1_set_drr(
OTG_FORCE_LOCK_ON_EVENT, 0,
OTG_SET_V_TOTAL_MIN_MASK_EN, 0,
OTG_SET_V_TOTAL_MIN_MASK, 0);
- }
- // Setup manual flow control for EOF via TRIG_A
- optc->funcs->setup_manual_trigger(optc);
+ // Setup manual flow control for EOF via TRIG_A
+ optc->funcs->setup_manual_trigger(optc);
+
+ } else {
+ REG_UPDATE_4(OTG_V_TOTAL_CONTROL,
+ OTG_SET_V_TOTAL_MIN_MASK, 0,
+ OTG_V_TOTAL_MIN_SEL, 0,
+ OTG_V_TOTAL_MAX_SEL, 0,
+ OTG_FORCE_LOCK_ON_EVENT, 0);
+
+ optc->funcs->set_vtotal_min_max(optc, 0, 0);
+ }
}
Looks like both the if and the else side paths end up programming
OTG_V_TOTAL_CONTROL differently after the change. Perhaps
OTG_SET_V_TOTAL_MIN_MASK needs to be set differently depending on the
DMCUB firmware version? @Mikhail Gavrilov does this patch fix it?
diff --git a/drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c
b/drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c
index 336488c0574e..933c7a342936 100644
--- a/drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c
+++ b/drivers/gpu/drm/amd/display/dc/optc/dcn10/dcn10_optc.c
@@ -944,7 +944,7 @@ void optc1_set_drr(
OTG_V_TOTAL_MAX_SEL, 1,
OTG_FORCE_LOCK_ON_EVENT, 0,
OTG_SET_V_TOTAL_MIN_MASK_EN, 0,
- OTG_SET_V_TOTAL_MIN_MASK, 0);
+ OTG_SET_V_TOTAL_MIN_MASK, (1 << 1)); /* TRIGA */
// Setup manual flow control for EOF via TRIG_A
optc->funcs->setup_manual_trigger(optc);
Thanks,
Alex
>
> --
> Best Regards,
> Mike Gavrilov.