On 27-05-21, 16:30, Rob Clark wrote:
On Wed, May 26, 2021 at 8:00 AM Jeffrey Hugo jeffrey.l.hugo@gmail.com wrote:
On Tue, May 25, 2021 at 11:46 PM Vinod Koul vkoul@kernel.org wrote:
Frankly, I don't like the MSM ACPI solution that I've seen on the laptops. The ACPI assumes the entire MDSS (including DSI parts) and GPU is one device, and ultimately handled by one driver. That driver needs to get a value from UEFI (set by the bootloader) that is the "panel id". Then the driver calls into ACPI (I think its _ROM, but I might be mistaken, doing this from memory) with that id. It gets back a binary blob which is mostly an xml file (format is publicly documented) that contains the panel timings and such.
tbh, I kinda suspect that having a single "gpu" device (which also includes venus, in addition to display, IIRC) in the ACPI tables is a windowsism, trying to make things look to userspace like a single "GPU card" in the x86 world.. but either way, I think the ACPI tables on the windows arm laptops which use dsi->bridge->edp is too much of a lost cause to even consider here. Possibly ACPI boot on these devices would be more feasible on newer devices which have direct eDP out of the SoC without requiring external bridge/panel glue.
yeah that is always a very different world. although it might make sense to use information in tables and try to deduce information about the system can be helpful...
I'd worry more about what makes sense in a DT world, when it comes to DT bindings.
And do you have thoughts on that..?