On Mon, Aug 29, 2022 at 07:56:40AM +0100, Hashim Mahmoud wrote:
> This iMac's screen works fine, but always turns off when the radeon GPU
> driver is loaded on any UNIX (tried Linux Mint and NomadBSD as well). I
> had to install OpenBSD on another machine since I was installing to an
> SD card, as I didn't have any (big enough) spare SSDs or USBs, and
> writing to the SD card from the installer on the same iMac gives me
> permission errors.
>
> I had installed the radeon firmware already by the time I put the SD
> card into the iMac. The GPU seems to work fine and I can login and run
> commands blindly, but the display is off... until I had the bright
> idea to connect a display over the DisplayPort at boot time, via a VGA
> to mini DisplayPort adapter. The internal eDP display worked, but the
> tty framebuffer took the resolution of the external display (similar to
> what would happen when a low resolution laptop is connected to a
> higher resolution display, and both displays are on), which is
> 1440x900, and the external display receives no output, though Xorg
> seems to acknowledge its existence and renders itself as if that
> display exists, as the xenodm login window is not available on the main
> display, and the mouse disappears as if it went to another display when
> hitting the left edge. I can login blind and run `xrandr --output
> DisplayPort-0 --off`, and everything seems to work perfectly fine and
> GPU accelerated, as the output of `glxinfo -B` indicates, and glxgears
> runs smoothly.
>
> However, this only works if the DisplayPort is connected at boot time:
>
> - If it is disconnected after the radeon driver is loaded, but X hasn't
> started yet, then the display goes black again, but I can plug it back
> in and the display shows up as normal (still in 1440x900, though), and
> I get this in blue: `[drm] *ERROR* chosen encoder in use 0`. No idea
> what that means.
>
> - Once X is started however, I can just disconnect the DisplayPort, and
> life is good :) ... except I get the following in xconsole:
> ```
> [drm] *ERROR* displayport link status failed
> [drm] *ERROR* clock recovery failed
> [drm] *ERROR* displayport link status failed
> [drm] *ERROR* clock recovery failed
> ```
> - Doesn't seem to effect me in any way, though.
>
> - I also get this error message, when I switch from my X session to
> tty: `[drm] *ERROR* rv770_restrict_performance_levels_before_switch
> failed`. Also seems to have no effect.
> - Note that these errors only appear in xconsole and not on the actual
> console in blue... weird.
>
>
> Is there some sort of software remedy for this? I doubt this (unless
> someone can tell me otherwise), so I was thinking of getting something
> like a Raspberry Pi Zero or an Arduino, and connecting to the
> DisplayPort, making it like some sort of dummy DisplayPort input by
> programming it... I'm not sure at all how to go about doing this, as
> I'm a very amateur programmer, but I know that it *should* be
> theoretically possible; any pointers would be very appreciated.
Does this help?
RV730 has DCE3.2
Index: sys/dev/pci/drm/radeon/atombios_encoders.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/drm/radeon/atombios_encoders.c,v
retrieving revision 1.17
diff -u -p -U6 -r1.17 atombios_encoders.c
--- sys/dev/pci/drm/radeon/atombios_encoders.c 24 Feb 2022 12:49:47 -0000
1.17
+++ sys/dev/pci/drm/radeon/atombios_encoders.c 29 Aug 2022 07:12:12 -0000
@@ -2189,13 +2189,14 @@ int radeon_atom_pick_dig_encoder(struct
/*
* On DCE32 any encoder can drive any block so usually just use crtc id,
* but Apple thinks different at least on iMac10,1, so there use linkb,
* otherwise the internal eDP panel will stay dark.
*/
if (ASIC_IS_DCE32(rdev)) {
- if (dmi_match(DMI_PRODUCT_NAME, "iMac10,1"))
+ if (dmi_match(DMI_PRODUCT_NAME, "iMac10,1") ||
+ dmi_match(DMI_PRODUCT_NAME, "iMac11,2"))
enc_idx = (dig->linkb) ? 1 : 0;
else
enc_idx = radeon_crtc->crtc_id;
goto assigned;
}
