On Thu, Dec 15, 2022 at 10:41:38AM +0100, Hans de Goede wrote:
> The apple-gmux driver only binds to old GMUX devices which have an
> IORESOURCE_IO resource (using inb()/outb()) rather then memory-mapped
> IO (IORESOURCE_MEM).
>
> T2 MacBooks use the new style GMUX devices (with IORESOURCE_MEM access),
> so these are not supported by the apple-gmux driver. This is not a problem
> since they have working ACPI video backlight support.
Interesting.
> +static bool apple_gmux_backlight_present(void)
> +{
> + struct acpi_device *adev;
> + struct device *dev;
> +
> + adev = acpi_dev_get_first_match_dev(GMUX_ACPI_HID, NULL, -1);
> + if (!adev)
> + return false;
> +
> + dev = acpi_get_first_physical_node(adev);
> + if (!dev)
> + return false;
> +
> + /*
> + * drivers/platform/x86/apple-gmux.c only supports old style
> + * Apple GMUX with an IO-resource.
> + */
> + return pnp_get_resource(to_pnp_dev(dev), IORESOURCE_IO, 0) != NULL;
> +}
The T2 is represented by a PCI device with ID 106B:1802.
Instead of the above, how about amending apple_gmux_present()
with a simple check like this:
/* T2 Macs drive GMUX via MMIO, which is unsupported for now */
if (pci_dev_present({{PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x1802)}, {}}))
return false;
Thanks,
Lukas
