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Date:   Thu, 3 Aug 2023 10:48:57 +0200
From:   Maxime Ripard <mripard@kernel.org>
To:     Neil Armstrong <neil.armstrong@linaro.org>
Cc:     Daniel Vetter <daniel@ffwll.ch>,
        Michael Riesch <michael.riesch@wolfvision.net>,
        Sam Ravnborg <sam@ravnborg.org>,
        Sebastian Reichel <sre@kernel.org>,
        Gerald Loacker <gerald.loacker@wolfvision.net>,
        David Airlie <airlied@gmail.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Conor Dooley <conor+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Rob Herring <robh+dt@kernel.org>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 0/4] drm/panel: sitronix-st7789v: add support for partial
 mode
Message-ID: <ekmwiy3iuvtqtb6hwjbba2ia3aemt3dxmx6dj3zh6ljfmuim4w@4jzhqdenxth4>
References: <20230718-feature-lcd-panel-v1-0-e9a85d5374fd@wolfvision.net>
 <292c3e7d-82ea-2631-bd4b-ef747f56287c@linaro.org>
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On Thu, Aug 03, 2023 at 10:11:22AM +0200, Neil Armstrong wrote:
> Hi,
>=20
> On 18/07/2023 17:31, Michael Riesch wrote:
> > Hi all,
> >=20
> > 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.
> >=20
> > Note: This series is already based on
> > https://lore.kernel.org/lkml/20230714013756.1546769-1-sre@kernel.org/
>=20
> 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.
>=20
> 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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