Before the drm driver had support for this file there was a driver that
exposed the contents of the vga password register to userspace. It would
present the entire register instead of interpreting it.
The drm implementation chose to mask of the lower bit, without explaining
why. This breaks the existing userspace, which is looking for 0xa8 in
the lower byte.
Change our implementation to expose the entire register.
Fixes: 696029eb36 ("drm/aspeed: Add sysfs for output settings")
Reported-by: Oskar Senft <osk@google.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Jeremy Kerr <jk@codeconstruct.com.au>
Tested-by: Oskar Senft <osk@google.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20211117010145.297253-1-joel@jms.id.au
There are minor differences in the values for the threshold value and
the scan line size between families of ASPEED SoC. Additionally the SCU
registers for the output control and scratch registers differ between
families.
This adds device tree matching to parameterise these values, allowing us
to add support for the AST2400 now, and in the future the AST2600.
Reviewed-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Link: https://patchwork.freedesktop.org/patch/msgid/20210209123734.130483-3-joel@jms.id.au
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
The following backtrace is seen when running aspeed G5 kernels.
WARNING: CPU: 0 PID: 1 at drivers/gpu/drm/drm_fb_helper.c:2233 drm_fbdev_generic_setup+0x138/0x198
aspeed_gfx 1e6e6000.display: Device has not been registered.
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.8.0-rc3 #1
Hardware name: Generic DT based system
Backtrace:
[<8010d6d0>] (dump_backtrace) from [<8010d9b8>] (show_stack+0x20/0x24)
r7:00000009 r6:60000153 r5:00000000 r4:8119fa94
[<8010d998>] (show_stack) from [<80b8cb98>] (dump_stack+0xcc/0xec)
[<80b8cacc>] (dump_stack) from [<80123ef0>] (__warn+0xd8/0xfc)
r7:00000009 r6:80e62ed0 r5:00000000 r4:974c3ccc
[<80123e18>] (__warn) from [<80123f98>] (warn_slowpath_fmt+0x84/0xc4)
r9:00000009 r8:806a0140 r7:000008b9 r6:80e62ed0 r5:80e631f8 r4:974c2000
[<80123f18>] (warn_slowpath_fmt) from [<806a0140>] (drm_fbdev_generic_setup+0x138/0x198)
r9:00000001 r8:9758fc10 r7:9758fc00 r6:00000000 r5:00000020 r4:9768a000
[<806a0008>] (drm_fbdev_generic_setup) from [<806d4558>] (aspeed_gfx_probe+0x204/0x32c)
r7:9758fc00 r6:00000000 r5:00000000 r4:9768a000
[<806d4354>] (aspeed_gfx_probe) from [<806dfca0>] (platform_drv_probe+0x58/0xa8)
Since commit 1aed9509b2 ("drm/fb-helper: Remove return value from
drm_fbdev_generic_setup()"), drm_fbdev_generic_setup() must be called
after drm_dev_register() to avoid the warning. Do that.
Fixes: 1aed9509b2 ("drm/fb-helper: Remove return value from drm_fbdev_generic_setup()")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20200701001002.74997-1-linux@roeck-us.net
