linux-kernel - [PATCH 5.15 828/917] drm/i915/fb: Fix rounding error in subsampled plane size calculation

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Date:   Mon, 15 Nov 2021 18:05:23 +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, Imre Deak <imre.deak@...el.com>,
        Juha-Pekka Heikkila <juhapekka.heikkila@...il.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 828/917] drm/i915/fb: Fix rounding error in subsampled plane size calculation

From: Imre Deak <imre.deak@...el.com>

[ Upstream commit 90ab96f3872eae816f4e07deaa77322a91237960 ]

For NV12 FBs with odd main surface tile-row height the CCS surface
height was incorrectly calculated 1 less than the actual value. Fix this
by rounding up the result of divison. For consistency do the same for
the CCS surface width calculation.

Fixes: b3e57bccd68a ("drm/i915/tgl: Gen-12 render decompression")
Signed-off-by: Imre Deak <imre.deak@...el.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@...il.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211026225105.2783797-2-imre.deak@intel.com
(cherry picked from commit 2ee5ef9c934ad26376c9282171e731e6c0339815)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/i915/display/intel_fb.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fb.c b/drivers/gpu/drm/i915/display/intel_fb.c
index c60a81a81c09c..c6413c5409420 100644
--- a/drivers/gpu/drm/i915/display/intel_fb.c
+++ b/drivers/gpu/drm/i915/display/intel_fb.c
@@ -172,8 +172,9 @@ static void intel_fb_plane_dims(const struct intel_framebuffer *fb, int color_pl
 
 	intel_fb_plane_get_subsampling(&main_hsub, &main_vsub, &fb->base, main_plane);
 	intel_fb_plane_get_subsampling(&hsub, &vsub, &fb->base, color_plane);
-	*w = fb->base.width / main_hsub / hsub;
-	*h = fb->base.height / main_vsub / vsub;
+
+	*w = DIV_ROUND_UP(fb->base.width, main_hsub * hsub);
+	*h = DIV_ROUND_UP(fb->base.height, main_vsub * vsub);
 }
 
 static u32 intel_adjust_tile_offset(int *x, int *y,
-- 
2.33.0