[PATCH 1/3] RFT: drm/pl111: Support grayscale

[Linus Walleij]

On Thu, Jul 25, 2019 at 9:26 PM Fabian Vogt <fabian at ritter-vogt.de> wrote:

> On a real CX the LCD displays shows content without
> any other changes to the set, but has a ~3Hz pulsating effect scrolling from
> the top to the bottom and the gray text changes color slightly.

So you mean something meaningful appears in the LCD
but there are visual disturbances?

> Without the patchset applied everything looks perfectly.
>
> I tried setting vrefresh to 20, fb_bpp to 16 and forcing an inverted panel
> clock, but the pulsing didn't change.
>
> Using the emulated CX I compared the contents of the registers and found
> that only the IPC bit (which I tried to set, so that's likely not it) and
> the interrupt registers have a different content.
>
> Any idea?

I think it's the clock settings in patch 2/3.

I just set them to "1000" (1MHz since its in kHz) based on some
educated guesses.

The old driver set the clock to "1" (kHz) so just try that first,
maybe it is really that slow.

It's just that the old driver also set refres to 60 fps which doesn't
add up, but I think that setting is simply ignored and that is why
it works.

Yours,
Linus Walleij

Yours,
Linus Walleij

Yours,
Linus Walleij