On Tue, May 31, 2022 at 6:56 PM Hans de Goede hdegoede@redhat.com wrote:
Hi,
On 5/30/22 13:34, Hsin-Yi Wang wrote:
On Mon, May 30, 2022 at 4:53 PM Hans de Goede hdegoede@redhat.com wrote:
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?
Right.
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.
Most panels set this value very late, in .get_modes callback (since it is when the connector is known), though the value was known during panel probe.
Hmm I would expect the main drm/kms driver to register the drm_connector object after probing the panel, right ?
So maybe this is a problem with the panel API? How about adding separate callback to the panel API to get the orientation, which the main drm/kms driver can then call before registering the connector ?
And then have the main drm/kms driver call drm_connector_set_panel_orientation() with the returned orientation on the connecter before registering it.
The new get_orientation callback for the panel should of course be optional (IOW amy be NULL), so we probably want a small helper for drivers using panel (sub)drivers to take care of the process of getting the panel orientation from the panel (if supported) and then setting it on the connector.
Hi Hans,
Thanks for the suggestion. I've sent a new version for this: https://patchwork.kernel.org/project/dri-devel/patch/20220601081823.1038797-...
Panel can implement the optional callback to return the orientation property, while drm/kms driver will call a drm API to get the value then they can call drm_connector_set_panel_orientation(). Panel .get_mode will still call drm_connector_set_panel_orientation() but now it will be a no-op as the value was set by drm/kms driver previously.
This is similar to the small patch below: https://patchwork.kernel.org/project/linux-mediatek/patch/20220530113033.124... But it's now using the panel API.
I think we can also let drm check if they have remote panel nodes: If there is a panel and the panel sets the orientation, let the drm read this value and set the property. Does this workflow sound reasonable?
The corresponding patch to implement this: https://patchwork.kernel.org/project/linux-mediatek/patch/20220530113033.124...
That is a suprisingly small patch (which is good). I guess that my suggestion to add a new panel driver callback to get the orientation would be a bit bigget then this. Still I think that that would be a bit cleaner, as it would also solve this for cases where the orientation comes from the panel itself (through say some EDID extenstion) rather then from devicetree.
Still I think either way should be acceptable upstream.
Opinions from other drm devs on the above are very much welcome!
Your small patch nicely avoids the probe ordering problem, so it is much better then this patch series.
Regards,
Hans
Thanks
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(-)