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

From: Hans de Goede <hdegoede@redhat.com>
To: Hsin-Yi Wang <hsinyi@chromium.org>,
	dri-devel@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel@ffwll.ch>,
	amd-gfx@lists.freedesktop.org, intel-gfx@lists.freedesktop.org
Cc: Rob Clark <robdclark@chromium.org>,
	Stephen Boyd <swboyd@chromium.org>,
	Douglas Anderson <dianders@chromium.org>,
	Chun-Kuang Hu <chunkuang.hu@kernel.org>,
	Sean Paul <sean@poorly.run>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	Simon Ser <contact@emersion.fr>,
	Harry Wentland <harry.wentland@amd.com>,
	Alex Deucher <alexander.deucher@amd.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Emil Velikov <emil.l.velikov@gmail.com>
Subject: Re: [PATCH v10 0/4] Separate panel orientation property creating and value setting
Date: Mon, 30 May 2022 10:53:11 +0200	[thread overview]
Message-ID: <a8d1fe13-e747-016a-2d45-bfb50f23f2d9@redhat.com> (raw)
In-Reply-To: <20220530081910.3947168-1-hsinyi@chromium.org>

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(-)
> 

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