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SubjectRe: [Letux-kernel] [BUG] SPI broken for SPI based panel drivers
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> Am 01.12.2020 um 17:44 schrieb Andreas Kemnade <andreas@kemnade.info>:
>
> 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?!

Apparently, because there was patch f1f028ff89cb0d3 to fix 6953c57ab172 ...

BR,
Nikolaus

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