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* [Intel-gfx] [PATCH] drm/i915/dsi: let HW maintain the HS-TRAIL timing
@ 2021-11-10 10:23 William Tseng
  2021-11-10 14:32 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
                   ` (7 more replies)
  0 siblings, 8 replies; 11+ messages in thread
From: William Tseng @ 2021-11-10 10:23 UTC (permalink / raw)
  To: intel-gfx; +Cc: Cooper Chiou, William Tseng

This change is to avoid over-specification of the TEOT timing
parameter, which is derived from software in current design.

Supposed that THS-TRAIL and THS-EXIT have the minimum values,
i.e., 60 and 100 in ns. If SW is overriding the HW default,
the TEOT value becomes 150 ns, approximately calculated by
the following formula.

  DIV_ROUND_UP(60/50)*50 + DIV_ROUND_UP(100/50))*50/2, where 50
  is LP Escape Clock time in ns.

The TEOT value 150 ns is larger than the maximum value,
around 136 ns if UI is 1.8ns, (105 ns + 12*UI, defined by MIPI
DPHY specification).

However, the TEOT value will meet the specification if THS-TRAIL
is set to the HW default, instead of software overriding.

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Cc: Lee Shawn C <shawn.c.lee@intel.com>
Cc: Cooper Chiou <cooper.chiou@intel.com>
Signed-off-by: William Tseng <william.tseng@intel.com>
---
 drivers/gpu/drm/i915/display/icl_dsi.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
index 168c84a74d30..0d22d3ed9734 100644
--- a/drivers/gpu/drm/i915/display/icl_dsi.c
+++ b/drivers/gpu/drm/i915/display/icl_dsi.c
@@ -1957,8 +1957,6 @@ static void icl_dphy_param_init(struct intel_dsi *intel_dsi)
 					 HS_PREPARE(prepare_cnt) |
 					 HS_ZERO_OVERRIDE |
 					 HS_ZERO(hs_zero_cnt) |
-					 HS_TRAIL_OVERRIDE |
-					 HS_TRAIL(trail_cnt) |
 					 HS_EXIT_OVERRIDE |
 					 HS_EXIT(exit_zero_cnt));
 
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2022-01-04  6:12 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-11-10 10:23 [Intel-gfx] [PATCH] drm/i915/dsi: let HW maintain the HS-TRAIL timing William Tseng
2021-11-10 14:32 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
2021-11-10 17:37 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
2021-11-15  3:03 ` [Intel-gfx] [PATCH v2] " William Tseng
2021-12-17 10:09   ` [Intel-gfx] [PATCH v3] " William Tseng
2022-01-04  6:11     ` Kulkarni, Vandita
2021-11-15  3:16 ` [Intel-gfx] ✗ Fi.CI.DOCS: warning for drm/i915/dsi: let HW maintain the HS-TRAIL timing (rev2) Patchwork
2021-11-15  3:36 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-11-15  5:14 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
2021-12-17 13:21 ` [Intel-gfx] ✓ Fi.CI.BAT: success for drm/i915/dsi: let HW maintain the HS-TRAIL timing (rev3) Patchwork
2021-12-17 15:07 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork

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