linux/drivers/gpu
Chen-Yu Tsai 4396393fb9
drm/sun4i: tcon: Set RGB DCLK min. divider based on hardware model
In commit 0b8e7bbde5 ("drm/sun4i: tcon: Set min division of TCON0_DCLK
to 1.") it was assumed that all TCON variants support a minimum divider
of 1 if only DCLK was used.

However, the oldest generation of hardware only supports minimum divider
of 4 if only DCLK is used. If a divider of 1 was used on this old
hardware, some scrolling artifact would appear. A divider of 2 seemed
OK, but a divider of 3 had artifacts as well.

Set the minimum divider when outputing to parallel RGB based on the
hardware model, with a minimum of 4 for the oldest (A10/A10s/A13/A20)
hardware, and a minimum of 1 for the rest. A value is not set for the
TCON variants lacking channel 0.

This fixes the scrolling artifacts seen on my A13 tablet.

Fixes: 0b8e7bbde5 ("drm/sun4i: tcon: Set min division of TCON0_DCLK to 1.")
Cc: <stable@vger.kernel.org> # 5.4.x
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20200107070113.28951-1-wens@kernel.org
2020-01-07 15:56:40 +01:00
..
drm drm/sun4i: tcon: Set RGB DCLK min. divider based on hardware model 2020-01-07 15:56:40 +01:00
host1x gpu: host1x: Unconditionally select IOMMU_IOVA 2019-11-01 10:49:17 +01:00
ipu-v3 gpu: ipu-v3: image-convert: only sample into the next tile if necessary 2019-08-19 16:25:30 +02:00
vga
Makefile