linux-kernel - Re: [PATCH v10 0/4] Separate panel orientation property creating and value setting

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Date:   Mon, 30 May 2022 10:53:11 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Hsin-Yi Wang <hsinyi@...omium.org>,
        dri-devel@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org
Cc:     Rob Clark <robdclark@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Sean Paul <sean@...rly.run>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Simon Ser <contact@...rsion.fr>,
        Harry Wentland <harry.wentland@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Emil Velikov <emil.l.velikov@...il.com>
Subject: Re: [PATCH v10 0/4] Separate panel orientation property creating and
 value setting

Hi,

On 5/30/22 10:19, Hsin-Yi Wang wrote:
> Some drivers, eg. mtk_drm and msm_drm, rely on the panel to set the
> orientation. Panel calls drm_connector_set_panel_orientation() to create
> orientation property and sets the value. However, connector properties
> can't be created after drm_dev_register() is called. The goal is to
> separate the orientation property creation, so drm drivers can create it
> earlier before drm_dev_register().

Sorry for jumping in pretty late in the discussion (based on the v10
I seem to have missed this before).

This sounds to me like the real issue here is that drm_dev_register()
is getting called too early?

To me it seems sensible to delay calling drm_dev_register() and
thus allowing userspace to start detecting available displays +
features until after the panel has been probed.

I see a devicetree patch in this series, so I guess that the panel
is described in devicetree. Especially in the case of devicetree
I would expect the kernel to have enough info to do the right
thing and make sure the panel is probed before calling
drm_dev_register() ?

Regards,

Hans




> 
> After this series, drm_connector_set_panel_orientation() works like
> before. It won't affect existing callers of
> drm_connector_set_panel_orientation(). The only difference is that
> some drm drivers can call drm_connector_init_panel_orientation_property()
> earlier.
> 
> Hsin-Yi Wang (4):
>   gpu: drm: separate panel orientation property creating and value
>     setting
>   drm/mediatek: init panel orientation property
>   drm/msm: init panel orientation property
>   arm64: dts: mt8183: Add panel rotation
> 
>  .../arm64/boot/dts/mediatek/mt8183-kukui.dtsi |  1 +
>  drivers/gpu/drm/drm_connector.c               | 58 ++++++++++++++-----
>  drivers/gpu/drm/mediatek/mtk_dsi.c            |  7 +++
>  drivers/gpu/drm/msm/dsi/dsi_manager.c         |  4 ++
>  include/drm/drm_connector.h                   |  2 +
>  5 files changed, 59 insertions(+), 13 deletions(-)
>