On Thu, 05 Mar 2020, Rajat Jain rajatja@google.com wrote:
On Thu, Mar 5, 2020 at 1:41 AM Jani Nikula jani.nikula@linux.intel.com wrote:
On Wed, 04 Mar 2020, Rajat Jain rajatja@google.com wrote:
- See if we can postpone creating and attaching properties to connector
->late_register hook. (I didn't have the time to look into it yet, at all.)
Apparently not. The drm core doesn't like to add properties in late_register() callback. I just tried it and get this warning:
I kind of had a feeling this would be the case, thanks for checking.
- Provide a way to populate connector->acpi_device_id and
connector->acpi_handle on a per-connector basis. At least the device id remains constant for the lifetime of the drm_device
Are you confirming that the connector->acpi_device_id remains constant for the lifetime of the drm_device, as calculated in intel_acpi_device_id_update()? Even in the face of external displays (monitors) being connected and disconnected during the lifetime of the system? If so, then I think we can have a solution.
First I thought so. Alas it does not hold for DP MST, where you can have connectors added and removed dynamically. I think we could ensure they stay the same for all other connectors though. I'm pretty sure this is already the case; they get added/removed after all others.
Another thought, from the ACPI perspective, I'm not sure the dynamically added/removed DP MST connectors should even have acpi handles. But again, tying all this together with ACPI stuff is not something I am an expert on.
(why do we keep updating it at every resume?!) but can we be sure ->acpi_handle does too? (I don't really know my way around ACPI.)
I don't understand why this was being updated on every resume in that case (this existed even before my patchset). I believe we do not need it. Yes, the ->acpi_handle will not change if the ->acpi_device_id does not change. I believe the way forward should then be to populate connector->acpi_device_id and connector->acpi_handle ONE TIME at the time of connector init (and not update it on every resume). Does this sound ok?
If a DP MST connector gets removed, should the other ACPI display indexes after that shift, or remain the same? I really don't know.
BR, Jani.