Commit 90caf1df authored by Orlando Chamberlain's avatar Orlando Chamberlain Committed by Hans de Goede
Browse files

platform/x86: apple-gmux: use first bit to check switch state 



On T2 Macs with MMIO gmux, when GMUX_PORT_SWITCH_DISPLAY is read, it can
have values of 2, 3, 4, and 5. Odd values correspond to the discrete gpu,
and even values correspond to the integrated gpu. The current logic is
that only 2 corresponds to IGD, but this doesn't work for T2 Macs.
Instead, check the first bit to determine the connected gpu.

As T2 Macs with gmux only can switch the internal display, it is
untested if this change (or a similar change) would be applicable
to GMUX_PORT_SWITCH_DDC and GMUX_PORT_SWITCH_EXTERNAL.

Reviewed-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarOrlando Chamberlain <orlandoch.dev@gmail.com>
Link: https://lore.kernel.org/r/20230303112842.3094-2-orlandoch.dev@gmail.com


Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
parent fe15c26e

drivers/platform/x86/apple-gmux.c

+3 −3
Original line number Diff line number Diff line
@@ -346,10 +346,10 @@ static void gmux_read_switch_state(struct apple_gmux_data *gmux_data) 
	else

		gmux_data->switch_state_ddc = VGA_SWITCHEROO_DIS;



	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_DISPLAY) == 2)

		gmux_data->switch_state_display = VGA_SWITCHEROO_IGD;

	else

	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_DISPLAY) & 1)

		gmux_data->switch_state_display = VGA_SWITCHEROO_DIS;

	else

		gmux_data->switch_state_display = VGA_SWITCHEROO_IGD;



	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL) == 2)

		gmux_data->switch_state_external = VGA_SWITCHEROO_IGD;