LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Geert Uytterhoeven <geert+renesas@glider.be>
To: "Noralf Trønnes" <noralf@tronnes.org>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Sean Paul" <sean@poorly.run>, "David Airlie" <airlied@linux.ie>,
	"Daniel Vetter" <daniel@ffwll.ch>
Cc: Thierry Reding <treding@nvidia.com>,
	dri-devel@lists.freedesktop.org,
	linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH] drm/mipi_dbi: Fix off-by-one bugs in mipi_dbi_blank()
Date: Mon, 30 Dec 2019 14:06:04 +0100
Message-ID: <20191230130604.31006-1-geert+renesas@glider.be> (raw)

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>
---
 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 e34058c721becd6b..16bff1be4b8ac622 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);
 
-- 
2.17.1


             reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-30 13:06 Geert Uytterhoeven [this message]
2020-01-02 14:52 ` Noralf Trønnes

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191230130604.31006-1-geert+renesas@glider.be \
    --to=geert+renesas@glider.be \
    --cc=airlied@linux.ie \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=maarten.lankhorst@linux.intel.com \
    --cc=mripard@kernel.org \
    --cc=noralf@tronnes.org \
    --cc=sean@poorly.run \
    --cc=treding@nvidia.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git