linux-kernel - [PATCH 5.4 133/434] drm/amd/display: Properly round nominal frequency for SPD

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Date:   Sun, 29 Dec 2019 18:23:06 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Aric Cyr <aric.cyr@....com>,
        Anthony Koo <Anthony.Koo@....com>,
        Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 133/434] drm/amd/display: Properly round nominal frequency for SPD

From: Aric Cyr <aric.cyr@....com>

[ Upstream commit c59802313e84bede954235b3a5dd0dd5325f49c5 ]

[Why]
Some displays rely on the SPD verticle frequency maximum value.
Must round the calculated refresh rate to the nearest integer.

[How]
Round the nominal calculated refresh rate to the nearest whole
integer.

Signed-off-by: Aric Cyr <aric.cyr@....com>
Reviewed-by: Anthony Koo <Anthony.Koo@....com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../gpu/drm/amd/display/modules/freesync/freesync.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
index ec70c9b12e1a..0978c698f0f8 100644
--- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
+++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c
@@ -743,6 +743,10 @@ void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync,
 	nominal_field_rate_in_uhz =
 			mod_freesync_calc_nominal_field_rate(stream);
 
+	/* Rounded to the nearest Hz */
+	nominal_field_rate_in_uhz = 1000000ULL *
+			div_u64(nominal_field_rate_in_uhz + 500000, 1000000);
+
 	min_refresh_in_uhz = in_config->min_refresh_in_uhz;
 	max_refresh_in_uhz = in_config->max_refresh_in_uhz;
 
@@ -996,14 +1000,13 @@ unsigned long long mod_freesync_calc_nominal_field_rate(
 			const struct dc_stream_state *stream)
 {
 	unsigned long long nominal_field_rate_in_uhz = 0;
+	unsigned int total = stream->timing.h_total * stream->timing.v_total;
 
-	/* Calculate nominal field rate for stream */
+	/* Calculate nominal field rate for stream, rounded up to nearest integer */
 	nominal_field_rate_in_uhz = stream->timing.pix_clk_100hz / 10;
 	nominal_field_rate_in_uhz *= 1000ULL * 1000ULL * 1000ULL;
-	nominal_field_rate_in_uhz = div_u64(nominal_field_rate_in_uhz,
-						stream->timing.h_total);
-	nominal_field_rate_in_uhz = div_u64(nominal_field_rate_in_uhz,
-						stream->timing.v_total);
+
+	nominal_field_rate_in_uhz =	div_u64(nominal_field_rate_in_uhz, total);
 
 	return nominal_field_rate_in_uhz;
 }
-- 
2.20.1