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

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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: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Orlando Chamberlain <orlandoch.dev@gmail.com>
Link: https://lore.kernel.org/r/20230303112842.3094-2-orlandoch.dev@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Orlando Chamberlain
2023-03-03 22:28:40 +11:00
committed by Hans de Goede
parent fe15c26ee2
commit 90caf1dfe9
1 changed files with 3 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/platform/x86/apple-gmux.c
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@@ -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;