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From:   Emil Velikov <emil.l.velikov@gmail.com>
Date:   Mon, 15 Jun 2020 23:26:29 +0100
Message-ID: <CACvgo51QuXMgWhFk4C=3rGvUZDX1_W0RZtVb5RtRPiHTpMebWQ@mail.gmail.com>
Subject: Re: [PATCH v2 0/5] 180 degrees rotation support for NVIDIA Tegra DRM
To:     Dmitry Osipenko <digetx@gmail.com>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Derek Basehore <dbasehore@chromium.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Sean Paul <sean@poorly.run>, linux-tegra@vger.kernel.org,
        "Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
        ML dri-devel <dri-devel@lists.freedesktop.org>
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Hi Dmitry,

On Mon, 15 Jun 2020 at 08:28, Dmitry Osipenko <digetx@gmail.com> wrote:
>
> Hello!
>
> This series adds 180=C2=B0 display plane rotation support to the NVIDIA T=
egra
> DRM driver which is needed for devices that have display panel physically
> mounted upside-down, like Nexus 7 tablet device for example [1]. Since
> DRM panel rotation is a new thing for a userspace, currently only
> Opentegra Xorg driver handles the rotated display panel [2], but this
> is good enough for the start.
>
> Note that later on it should be possible to implement a transparent 180=
=C2=B0
> display rotation for Tegra DRM driver which will remove the need to have
> a bleeding edge userspace that knows how to rotate display planes and I'm
> slowly working on it. For the starter we can go with the minimal rotation
> support, so it's not a blocker.
>
> This series is based on the work that was made by Derek Basehore for the
> Mediatek driver [3], his patch is included into this patchset. I added
> my tested-by tag to the Derek's patch.
>
> Please review and apply, thanks in advance!
>
> [1] https://patchwork.ozlabs.org/project/linux-tegra/patch/20200607154327=
.18589-3-digetx@gmail.com/
> [2] https://github.com/grate-driver/xf86-video-opentegra/commit/28eb20a39=
59bbe5bc3a3b67e55977093fd5114ca
> [3] https://lkml.org/lkml/2020/3/5/1119
>
> Changelog:
>
> v2: - Dropped "drm/panel: Set display info in panel attach" patch, which
>       turned out to be obsolete now.
>
>     - Renamed the cover-latter, hopefully this will fix the bouncing emai=
ls.
>
> Derek Basehore (1):
>   drm/panel: Add helper for reading DT rotation
>
> Dmitry Osipenko (4):
>   drm/panel: lvds: Set up panel orientation

IMHO it's perfectly reasonable to report the panel orientation to
userspace, which can apply plane rotation as needed.

Although I see that this series, alike Derek's, has a couple of issues:
 - only a single panel driver is updated
 - rotation is _not_ listed as supported property, in said panel
driver device-tree bindings

My personal inclination is that we should aim for a comprehensive solution:
 - wire all panel drivers, as currently documented (quick grep list below)
 - document and wire-up the lvds and boe panels - as proposed by you
and Derek respectively

HTH
Emil

Documentation/devicetree/bindings/display/himax,hx8357d.txt:2
Documentation/devicetree/bindings/display/ilitek,ili9225.txt:2
Documentation/devicetree/bindings/display/ilitek,ili9341.txt:2
Documentation/devicetree/bindings/display/ilitek,ili9486.yaml:2
Documentation/devicetree/bindings/display/multi-inno,mi0283qt.txt:2
Documentation/devicetree/bindings/display/panel/panel-common.yaml:2
Documentation/devicetree/bindings/display/sitronix,st7586.txt:1
Documentation/devicetree/bindings/display/sitronix,st7735r.yaml:2