From 2ce18249af5a28031b3f909cfafccc88ea966c9d 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: bsc#1114279

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
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tinydrm/mipi-dbi.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -293,9 +293,9 @@ static void mipi_dbi_blank(struct mipi_d
 	memset(mipi->tx_buf, 0, len);
 
 	mipi_dbi_command(mipi, MIPI_DCS_SET_COLUMN_ADDRESS, 0, 0,
-			 (width >> 8) & 0xFF, (width - 1) & 0xFF);
+			 ((width - 1) >> 8) & 0xFF, (width - 1) & 0xFF);
 	mipi_dbi_command(mipi, MIPI_DCS_SET_PAGE_ADDRESS, 0, 0,
-			 (height >> 8) & 0xFF, (height - 1) & 0xFF);
+			 ((height - 1) >> 8) & 0xFF, (height - 1) & 0xFF);
 	mipi_dbi_command_buf(mipi, MIPI_DCS_WRITE_MEMORY_START,
 			     (u8 *)mipi->tx_buf, len);
 }