Re: [PATCH] drm/radeon: fix eDP resume from suspend on iMac11, 1 / DCE3.1 systems

[Gilles Risch <gilles.risch@gmail.com>]

Am Mo., 18. Mai 2026 um 16:13 Uhr schrieb Alex Deucher <alexdeucher@gmail.com>:
>
> On Sat, May 16, 2026 at 2:52 PM Gilles Risch <gilles.risch@gmail.com> wrote:
> >
> > After suspend/resume the internal eDP display on iMac11,1 (and
> > potentially other DCE3.1 systems) stays dark because
> > atombios_set_edp_panel_power() skips panel power control for
> > anything older than DCE4.
> >
> > Fix this by:
> > - Extending atombios_set_edp_panel_power() to also handle DCE3.1
> >   by changing the !ASIC_IS_DCE4() guard to !ASIC_IS_DCE31().
> >   HPD polling works correctly on DCE3.1 (verified: HPD is asserted
> >   at iteration 0 on iMac11,1).
> > - Issuing ATOM_ENCODER_CMD_DP_VIDEO_ON/OFF for DCE3.1 in addition
> >   to DCE4+.
> >
> > Tested on iMac11,1 (Mobility Radeon HD 4850, RV770/DCE3.1).
> >
> > Signed-off-by: Gilles Risch <gilles.risch@gmail.com>
> > ---
> >  drivers/gpu/drm/radeon/atombios_encoders.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
> > index 4e984973c043..b62fd713efcf 100644
> > --- a/drivers/gpu/drm/radeon/atombios_encoders.c
> > +++ b/drivers/gpu/drm/radeon/atombios_encoders.c
> > @@ -1383,7 +1383,7 @@ atombios_set_edp_panel_power(struct drm_connector *connector, int action)
> >         if (connector->connector_type != DRM_MODE_CONNECTOR_eDP)
> >                 goto done;
> >
> > -       if (!ASIC_IS_DCE4(rdev))
> > +       if (!ASIC_IS_DCE31(rdev))
> >                 goto done;
> >
> >         if ((action != ATOM_TRANSMITTER_ACTION_POWER_ON) &&
> > @@ -1707,7 +1707,7 @@ radeon_atom_encoder_dpms_dig(struct drm_encoder *encoder, int mode)
> >                 if (ENCODER_MODE_IS_DP(atombios_get_encoder_mode(encoder)) && connector) {
> >                         /* DP_SET_POWER_D0 is set in radeon_dp_link_train */
> >                         radeon_dp_link_train(encoder, connector);
> > -                       if (ASIC_IS_DCE4(rdev))
> > +                       if (ASIC_IS_DCE4(rdev) || ASIC_IS_DCE31(rdev))
> >                                 atombios_dig_encoder_setup(encoder, ATOM_ENCODER_CMD_DP_VIDEO_ON, 0);
> >                 }
> >                 if (radeon_encoder->devices & (ATOM_DEVICE_LCD_SUPPORT)) {
> > @@ -1724,7 +1724,7 @@ radeon_atom_encoder_dpms_dig(struct drm_encoder *encoder, int mode)
> >         case DRM_MODE_DPMS_SUSPEND:
> >         case DRM_MODE_DPMS_OFF:
> >
> > -               if (ASIC_IS_DCE4(rdev)) {
> > +               if (ASIC_IS_DCE4(rdev) || ASIC_IS_DCE31(rdev)) {
> >                         if (ENCODER_MODE_IS_DP(atombios_get_encoder_mode(encoder)) && connector)
> >                                 atombios_dig_encoder_setup(encoder, ATOM_ENCODER_CMD_DP_VIDEO_OFF, 0);
> >                 }
>
> These changes don't make sense and will break other DCE3.c boards.   I
> had the attached patch from you in one of my old branches, does it fix
> the issue?
>
> Alex

While the initial attached patch resolved the dark screen issue after
a fresh boot, this follow-up patch addresses the same problem
occurring after resuming from suspend. Should I used dmi_match() to
avoid breaking other DCE3.c boards?

Regards,
Gilles