Hi Tomasz, On 1/26/22 12:58, Tomasz Figa wrote: > Hi Hans, > > +Ricardo Ribalda +Sergey Senozhatsky FYI > > On Mon, Jan 17, 2022 at 6:43 AM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: >> >> Hi All, >> >> IIRC there was some discussion about $subject a while ago, >> esp. being pushed by the ChromeOS folks (IIRC). If you know what >> I'm talking about, please add relevant folks to the Cc. >> >> While doing some work on atomisp support I noticed that the >> ACPI device fwnode-s describing the sensors have an ACPI _PLD >> method, which is a standardized ACPI method to retreive an >> package (ACPI for struct) describing the location of things >> like USB ports; and in this case of the camera sensors. >> >> And upon checking the Surface Go DSDT the sensors there seem to >> have the _PLD bits to. And in both cases at least the following >> PLD field (bits 67-69) seems to contain valid and relevant info, >> quoting from the ACPI spec 6.2 version, page 329: >> >> """ >> Panel: Describes which panel surface of the system’s housing >> the device connection point resides on: >> 0 – Top >> 1 – Bottom >> 2 – Left >> 3 – Right >> 4 – Front >> 5 – Back >> 6 – Unknown >> """ >> >> This seems to be consistently set to 4 or 5 for the _PLD method >> of the sensor ACPI nodes which I checked. >> >> So rather then defining a new devicetree property for this and >> embedding that inside the ACPI tables, IMHO it would be best if >> the ChromeOS devices would use the standardized _PLD ACPI method >> for this too. > > Thanks for bringing this to our attention. > > We don't seem to be using it in our ACPI tables, but I agree that it > sounds like something that should be populated. > > However, we probably still need something else to describe rotation > (as Laurent mentioned) Ack. > and position on the plane (when there is more > than one camera facing the same direction). The position on the device, relative to other sensors can also be described in an acpi _PLD package. Note I'm not sure of it is already being used this way anywhere though. Regards, Hans > > Best regards, > Tomasz >
