From 451e9f556639a5fbde196868a21e788cb550d152 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Mon, 30 Dec 2019 14:06:04 +0100
Subject: drm/mipi_dbi: Fix off-by-one bugs in mipi_dbi_blank()
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Git-commit: 2ce18249af5a28031b3f909cfafccc88ea966c9d
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
When configuring the frame memory window, the last column and row
numbers are written to the column resp. page address registers. These
numbers are thus one less than the actual window width resp. height.
While this is handled correctly in mipi_dbi_fb_dirty() since commit
03ceb1c8dfd1e293 ("drm/tinydrm: Fix setting of the column/page end
addresses."), it is not in mipi_dbi_blank(). The latter still forgets
to subtract one when calculating the most significant bytes of the
column and row numbers, thus programming wrong values when the display
width or height is a multiple of 256.
Fixes: 02dd95fe31693626 ("drm/tinydrm: Add MIPI DBI support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191230130604.31006-1-geert+renesas@glider.be
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/drm_mipi_dbi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
index e34058c721be..16bff1be4b8a 100644
--- a/drivers/gpu/drm/drm_mipi_dbi.c
+++ b/drivers/gpu/drm/drm_mipi_dbi.c
@@ -367,9 +367,9 @@ static void mipi_dbi_blank(struct mipi_dbi_dev *dbidev)
memset(dbidev->tx_buf, 0, len);
mipi_dbi_command(dbi, MIPI_DCS_SET_COLUMN_ADDRESS, 0, 0,
- (width >> 8) & 0xFF, (width - 1) & 0xFF);
+ ((width - 1) >> 8) & 0xFF, (width - 1) & 0xFF);
mipi_dbi_command(dbi, MIPI_DCS_SET_PAGE_ADDRESS, 0, 0,
- (height >> 8) & 0xFF, (height - 1) & 0xFF);
+ ((height - 1) >> 8) & 0xFF, (height - 1) & 0xFF);
mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START,
(u8 *)dbidev->tx_buf, len);
--
2.28.0