leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

DTS: ARM: gta04: introduce legacy spi-cs-high to make display work again

Browse Source 
commit 6953c57ab1 "gpio: of: Handle SPI chipselect legacy bindings"

did introduce logic to centrally handle the legacy spi-cs-high property
in combination with cs-gpios. This assumes that the polarity
of the CS has to be inverted if spi-cs-high is missing, even
and especially if non-legacy GPIO_ACTIVE_HIGH is specified.

The DTS for the GTA04 was orginally introduced under the assumption
that there is no need for spi-cs-high if the gpio is defined with
proper polarity GPIO_ACTIVE_HIGH.

This was not a problem until gpiolib changed the interpretation of
GPIO_ACTIVE_HIGH and missing spi-cs-high.

The effect is that the missing spi-cs-high is now interpreted as CS being
low (despite GPIO_ACTIVE_HIGH) which turns off the SPI interface when the
panel is to be programmed by the panel driver.

Therefore, we have to add the redundant and legacy spi-cs-high property
to properly activate CS.

Cc: stable@vger.kernel.org
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This commit is contained in:
H. Nikolaus Schaller 2019-09-20 18:11:15 +02:00 committed by Tony Lindgren
parent 2d3c8ba3cf
commit f1f028ff89
1 changed files with 1 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arm/boot/dts/omap3-gta04.dtsi
View File

@ -120,6 +120,7 @@
spi-max-frequency = <100000>;
spi-cpol;
spi-cpha;
spi-cs-high;
backlight= <&backlight>;
label = "lcd";