Thanks Alex, found that patch.
My patch is no more required.
From: Deucher, Alexander <Alexander.Deucher@xxxxxxx>
Sent: Monday, November 26, 2018 7:46 PM
To: S, Shirish <Shirish.S@xxxxxxx>; Li, Sun peng (Leo) <Sunpeng.Li@xxxxxxx>; Wentland, Harry <Harry.Wentland@xxxxxxx>
Cc: amd-gfx@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [PATCH] drm/amd/display: limit high pixel clock modes on ST/CZ
I thought there was a patch to do this already that got sent out a few weeks ago. Basically limit ST/CZ to modes that do not require a retimer. Is an additional patch needed?
Alex
[Why]
ST/CZ (dce110) advertises modes such as 4k@60Hz etc.,
that it cannot handle correctly, hence resulting in
several issues like flickering, black lines/flashes and so on.
[How]
These modes are basically high pixel clock ones, hence
limit the same to be advertised to avoid bad user experiences
Signed-off-by: Shirish S <shirish.s@xxxxxxx>
Suggested-by: Harry Wentland <harry.wentland@xxxxxxx>
---
.../gpu/drm/amd/display/dc/dce110/dce110_timing_generator.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_timing_generator.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_timing_generator.c
index 1b2fe0d..1b8fe99 100644
--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_timing_generator.c
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_timing_generator.c
@@ -1121,6 +1121,16 @@ bool dce110_timing_generator_validate_timing(
if (!timing)
return false;
+ /* Limit all modes that have a high pixel clock
+ * which seems to be problematic on dce110
+ * These include: 4k@60Hz, 1080p@144Hz,1440p@120Hz
+ * based on the below formula:
+ * refresh rate = pixel clock / (htotal * vtotal)
+ */
+ if (timing->pix_clk_khz > 300000)
+ return false;
+
+
hsync_offset = timing->h_border_right + timing->h_front_porch;
h_sync_start = timing->h_addressable + hsync_offset;
--
2.7.4
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