linux-kernel - [PATCH 5.15 55/73] drm/amd/display: clear optc underflow before turn off odm clock

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Date:   Fri,  2 Sep 2022 14:19:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alvin Lee <alvin.lee2@....com>,
        Tom Chung <chiahsuan.chung@....com>,
        Fudong Wang <Fudong.Wang@....com>,
        Daniel Wheeler <daniel.wheeler@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 55/73] drm/amd/display: clear optc underflow before turn off odm clock

From: Fudong Wang <Fudong.Wang@....com>

[ Upstream commit b2a93490201300a749ad261b5c5d05cb50179c44 ]

[Why]
After ODM clock off, optc underflow bit will be kept there always and clear not work.
We need to clear that before clock off.

[How]
Clear that if have when clock off.

Reviewed-by: Alvin Lee <alvin.lee2@....com>
Acked-by: Tom Chung <chiahsuan.chung@....com>
Signed-off-by: Fudong Wang <Fudong.Wang@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c
index 37848f4577b18..92fee47278e5a 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c
@@ -480,6 +480,11 @@ void optc1_enable_optc_clock(struct timing_generator *optc, bool enable)
 				OTG_CLOCK_ON, 1,
 				1, 1000);
 	} else  {
+
+		//last chance to clear underflow, otherwise, it will always there due to clock is off.
+		if (optc->funcs->is_optc_underflow_occurred(optc) == true)
+			optc->funcs->clear_optc_underflow(optc);
+
 		REG_UPDATE_2(OTG_CLOCK_CONTROL,
 				OTG_CLOCK_GATE_DIS, 0,
 				OTG_CLOCK_EN, 0);
-- 
2.35.1