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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Sung Lee <sung.lee@amd.com>,
        Tony Cheng <Tony.Cheng@amd.com>,
        Aurabindo Pillai <aurabindo.pillai@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 28/32] drm/amd/display: Update dram_clock_change_latency for DCN2.1
Date:   Fri,  5 Feb 2021 15:07:43 +0100
Message-Id: <20210205140653.533882006@linuxfoundation.org>
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References: <20210205140652.348864025@linuxfoundation.org>
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From: Jake Wang <haonan.wang2@amd.com>

[ Upstream commit 901c1ec05ef277ce9d43cb806a225b28b3efe89a ]

[WHY]
dram clock change latencies get updated using ddr4 latency table, but
does that update does not happen before validation. This value
should not be the default and should be number received from
df for better mode support.
This may cause a PState hang on high refresh panels with short vblanks
such as on 1080p 360hz or 300hz panels.

[HOW]
Update latency from 23.84 to 11.72.

Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c b/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
index bb7add5ea2273..a6d5beada6634 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c
@@ -257,7 +257,7 @@ struct _vcs_dpi_soc_bounding_box_st dcn2_1_soc = {
 	.num_banks = 8,
 	.num_chans = 4,
 	.vmm_page_size_bytes = 4096,
-	.dram_clock_change_latency_us = 23.84,
+	.dram_clock_change_latency_us = 11.72,
 	.return_bus_width_bytes = 64,
 	.dispclk_dppclk_vco_speed_mhz = 3600,
 	.xfc_bus_transport_time_us = 4,
-- 
2.27.0