linux-kernel - [PATCH 3/3] drm/tinydrm: Fix setting of the column/page end addresses.

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Date:   Wed, 24 Oct 2018 11:43:13 -0700
From:   Eric Anholt <eric@...olt.net>
To:     dri-devel@...ts.freedesktop.org,
        Noralf Trønnes <noralf@...nnes.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Heiner Kallweit <hkallweit1@...il.com>,
        Eric Anholt <eric@...olt.net>
Subject: [PATCH 3/3] drm/tinydrm: Fix setting of the column/page end addresses.

If the clipped dirty region's x/y happened to align to 256, we would
have set the top 8 bits wrong.  Noticed by inspection, not by
reproducing a bug.

Signed-off-by: Eric Anholt <eric@...olt.net>
---
 drivers/gpu/drm/tinydrm/mipi-dbi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
index cb3441e51d5f..1bb870021f6e 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -240,10 +240,10 @@ static int mipi_dbi_fb_dirty(struct drm_framebuffer *fb,
 
 	mipi_dbi_command(mipi, MIPI_DCS_SET_COLUMN_ADDRESS,
 			 (clip.x1 >> 8) & 0xFF, clip.x1 & 0xFF,
-			 (clip.x2 >> 8) & 0xFF, (clip.x2 - 1) & 0xFF);
+			 ((clip.x2 - 1) >> 8) & 0xFF, (clip.x2 - 1) & 0xFF);
 	mipi_dbi_command(mipi, MIPI_DCS_SET_PAGE_ADDRESS,
 			 (clip.y1 >> 8) & 0xFF, clip.y1 & 0xFF,
-			 (clip.y2 >> 8) & 0xFF, (clip.y2 - 1) & 0xFF);
+			 ((clip.y2 - 1) >> 8) & 0xFF, (clip.y2 - 1) & 0xFF);
 
 	ret = mipi_dbi_command_buf(mipi, MIPI_DCS_WRITE_MEMORY_START, tr,
 				(clip.x2 - clip.x1) * (clip.y2 - clip.y1) * 2);
-- 
2.19.1