On Thu, Jun 18, 2020 at 9:33 AM Hans Verkuil <hverkuil-cisco@xxxxxxxxx> wrote: > > On 18/06/2020 18:25, Jeff Chase wrote: > > On Thu, Jun 18, 2020 at 3:05 AM Hans Verkuil <hverkuil-cisco@xxxxxxxxx> wrote: > >> > >> On 18/06/2020 10:59, Jeff Chase wrote: > >>> Hi Hans, > >>> > >>> We are using two of these in an Intel-based Chromebox. I see that the > >>> cros-ec and seco drivers just statically define the PCI BDF of the > >>> Intel graphics device for their boards. I don't see an example of ACPI > >>> passing this information. I can copy cros-ec and seco by adding a > >>> board table and then use the UID of each device to select the correct > >>> port. Adding board-specific configuration to the driver doesn't seem > >>> ideal but I'm not sure what the proper way to pass this using ACPI is. > >> > >> You are right, it's not ACPI, it's using DMI matching. > >> > >> I have zero knowledge about ACPI, so I have no idea if there is some standard > >> method of retrieving this association via ACPI. > > > > I'm not very familiar with ACPI either. I looked for but did not find > > an ACPI equivalent of_get_mac_address(). > > > > I believe it's possible to reference the PCI node but it would take a > > bit of work on both the coreboot and linux side. > > > >> > >> This particular chip can actually be used both with DMI matching but also > >> on an ARM with device tree, but since you can't test this on an ARM board, > >> there is no point in adding support for that. > >> > >> However, compared to the cros-ec and seco drivers you can do something a bit > >> different here: those drivers just return -ENODEV if there is no match, but > >> since this driver reads the EDID it can just continue as long as it does not > >> set the CEC_CAP_CONNECTOR_INFO capability. > > > > Is it necessary to add support if we don't set CEC_CAP_CONNECTOR_INFO? > > It is very desirable. Otherwise userspace will not know which CEC device is associated > with which HDMI device. Since you are using two of these chips for a Chromebox, I > suspect that you actually need to support this. > > Also, I am (slowly) working on wiring support for this in all CEC transmitter drivers, > so I prefer not to add CEC drivers without support for this. Okay, understood. I'll look into using DMI matching. Thanks, Jeff > > I really should have noticed much earlier that support for this was missing. My > apologies for that. > > Regards, > > Hans
