linux-kernel - [PATCH 5.3 057/166] drm/amd/display: fix MPO HUBP underflow with Scatter Gather

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Message-Id: <20191006171217.910059397@linuxfoundation.org>
Date:   Sun,  6 Oct 2019 19:20:23 +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, Zi Yu Liao <ziyu.liao@....com>,
        Tony Cheng <Tony.Cheng@....com>,
        Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.3 057/166] drm/amd/display: fix MPO HUBP underflow with Scatter Gather

From: Zi Yu Liao <ziyu.liao@....com>

[ Upstream commit 89cb5614736b9b5d3b833ca2237d10da6b4b0395 ]

[why]
With Scatter Gather enabled, HUBP underflows during MPO enabled video
playback. hubp_init has a register write that fixes this problem, but
the register is cleared when HUBP gets power gated.

[how]
Make a call to hubp_init during enable_plane, so that the fix can
be applied after HUBP powers back on again.

Signed-off-by: Zi Yu Liao <ziyu.liao@....com>
Reviewed-by: Tony Cheng <Tony.Cheng@....com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
index f8abe98a576be..8fdb53a44bfb3 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
@@ -1110,6 +1110,9 @@ void dcn20_enable_plane(
 	/* enable DCFCLK current DCHUB */
 	pipe_ctx->plane_res.hubp->funcs->hubp_clk_cntl(pipe_ctx->plane_res.hubp, true);
 
+	/* initialize HUBP on power up */
+	pipe_ctx->plane_res.hubp->funcs->hubp_init(pipe_ctx->plane_res.hubp);
+
 	/* make sure OPP_PIPE_CLOCK_EN = 1 */
 	pipe_ctx->stream_res.opp->funcs->opp_pipe_clock_control(
 			pipe_ctx->stream_res.opp,
-- 
2.20.1