Joel Stanley 696029eb36 drm/aspeed: Add sysfs for output settings
These settings are used by an ASPEED BMC to determine when the host is
trying to drive the display over PCIe (vga_pw) and to switch the
output between PCIe and the internal graphics device (dac_mux).

The valid values for the dac mux are:

 00: VGA mode (default, aka PCIe)
 01: Graphics CRT (aka BMC internal graphics, this driver)
 10: Pass through mode from video input port A
 11: Pass through mode from video input port B

Values for the read-only vga password register are:

 1: Host driving the display
 0: Host not driving the display

Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://patchwork.freedesktop.org/patch/msgid/20200916083413.777307-1-joel@jms.id.au
2020-10-09 11:48:33 +10:30
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