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SubjectRe: [Letux-kernel] [BUG] SPI broken for SPI based panel drivers
On Tue, 1 Dec 2020 11:10:49 -0500
Sven Van Asbroeck <thesven73@gmail.com> wrote:

> Nikolaus,
>
> On Tue, Dec 1, 2020 at 9:38 AM H. Nikolaus Schaller <hns@goldelico.com> wrote:
> >
> > Let's work on a fix for the fix now.
> >
>
> Are you quite sure the chip-select of the tpo,td028ttec1 panel
> is active-high? A quick google produced a datasheet which
> seems to indicate that XCS is active-low?
>
Schematics is here:
https://projects.goldelico.com/p/gta04-main/downloads/48/

The display connector P204-LCD indicates some inversion at the XCS and
XRES pins.

This patch fixes things for a boot where the display was not
touched by the bootloader
diff --git a/arch/arm/boot/dts/omap3-gta04.dtsi b/arch/arm/boot/dts/omap3-gta04.dtsi
index c8745bc800f7..003202d12990 100644
--- a/arch/arm/boot/dts/omap3-gta04.dtsi
+++ b/arch/arm/boot/dts/omap3-gta04.dtsi
@@ -124,7 +124,6 @@
spi-max-frequency = <100000>;
spi-cpol;
spi-cpha;
- spi-cs-high;

backlight= <&backlight>;
label = "lcd";
So if that one is really active-low, why did it ever work?!

Regards,
Andreas

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