On Mon, Aug 29, 2022 at 10:03:34AM +0100, Hashim Mahmoud wrote:
> On Mon, 29 Aug 2022 17:19:16 +1000
> Jonathan Gray <j...@jsg.id.au> wrote:
>
> > 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;
> > }
>
> Sorry for the relatively late reply, this is my first time compiling
> the kernel from source... but man you're a life saver; it worked! I do
> get this error though:
> `WARNING bo->pin_count failed at /usr/src/sys/dev/pci/drm/ttm/ttm_bo.c:409`
> Which also doesn't affect me, but worth pointing out. I tried making an
> external monitor work over the DisplayPort, but seems to still have the
> problem of rendering but not actually outputting... I might've got the
> above error after I tried making the monitor work, I'm not sure, but
> not like it matters much; no external monitor isn't a deal breaker for
> me, but if there's a fix I'd gladly accept it.
>
> Is there a way to fix this on Linux or FreeBSD? iirc all the UNIXes
> share the same GPU drivers, so surely there's a fix. Thanks a lot, man.
I'm not sure this change is correct. When this problem came up in the
past, it was timing related.
sys/dev/pci/drm/include/linux/delay.h
----------------------------
revision 1.3
date: 2020/08/18 19:50:08; author: mglocker; state: Exp; lines: +1 -1;
commitid: 5kwux8n8bT8IM82I;
Our usleep_range(min, max) implementation today is only taking account
of the min value to delay. On the iMac11,2 this was too short, causing
a timeout in the DP AUX transaction retry loop, leaving the eDP dark
after the KMS initialization attempt. Affected code line for reference:
sys/dev/pci/drm/drm_dp_helper.c:771, revision 1.11
Therefore we change the behavior of usleep_range(min, max) to delay
the average value of min and max instead, which finally fixes the KMS
initialization on the iMac11,2.
Help and ok jsg@
----------------------------
