Re: [PATCH 0/4] drm/panel: sitronix-st7789v: add support for partial mode

From: Maxime Ripard
Date: Thu Aug 03 2023 - 04:49:13 EST


On Thu, Aug 03, 2023 at 10:11:22AM +0200, Neil Armstrong wrote:
> Hi,
>
> On 18/07/2023 17:31, Michael Riesch wrote:
> > Hi all,
> >
> > This series adds support for the partial display mode to the Sitronix
> > ST7789V panel driver. This is useful for panels that are partially
> > occluded by design, such as the Jasonic JT240MHQS-HWT-EK-E3. Support
> > for this particular panel is added as well.
> >
> > Note: This series is already based on
> > https://lore.kernel.org/lkml/20230714013756.1546769-1-sre@xxxxxxxxxx/
>
> I understand Maxime's arguments, but by looking closely at the code,
> this doesn't look like an hack at all and uses capabilities of the
> panel controller to expose a smaller area without depending on any
> changes or hacks on the display controller side which is coherent.
>
> Following's Daniel's summary we cannot compare it to TV overscan
> because overscan is only on *some* displays, we can still get 100%
> of the picture from the signal.

Still disagree on the fact that it only affects some display. But it's
not really relevant for that series.

I think I'll still like to have something clarified before we merge it:
if userspace forces a mode, does it contain the margins or not? I don't
have an opinion there, I just think it should be documented.

Maxime

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