Re: [PATCH v4] drm/radeon: fix internal display on iMac11, 1 (RV770/DCE3.1)

[Alex Deucher <alexdeucher@gmail.com>]

On Fri, May 29, 2026 at 3:43 AM Gilles Risch <gilles.risch@gmail.com> wrote:
>
> Good morning,
>
> I'll make that adjustment, shouldn't I just regroup all three iMac
> machines in one if statement?

Yeah, that works too.

Alex

>
> Am Do., 28. Mai 2026 um 20:53 Uhr schrieb Alex Deucher <alexdeucher@gmail.com>:
> >
> > On Thu, May 28, 2026 at 3:39 AM Gilles Risch <gilles.risch@gmail.com> wrote:
> > >
> > > The Apple iMac11,1 (27-inch, Late 2009) uses a Mobility Radeon HD 4850
> > > (RV770/DCE3.1) with a 2560x1440 internal panel on an internal
> > > DisplayPort path. Without this fix the display stays dark under KMS.
> > >
> > > The same problem already exists for iMac10,1 and iMac11,2. Three fixes:
> > >
> > > 1. Introduce ASIC_IS_DCE31() for CHIP_RV770 and newer. Note that
> > >    CHIP_RV770 precedes CHIP_RV730 in the enum, so ASIC_IS_DCE31()
> > >    subsumes ASIC_IS_DCE32().
> > >
> > > 2. Extend the Link B encoder quirk from ASIC_IS_DCE32() to
> > >    ASIC_IS_DCE31() and add iMac11,1 to the DMI list.
> > >
> > > 3. The 2560x1440 panel needs RADEON_PLL_USE_FRAC_FB_DIV and
> > >    ATOM_ENCODER_CMD_DP_VIDEO_ON. These are limited to iMac11,1
> > >    via dmi_match() to avoid affecting other DCE3.1 boards.
> > >
> > > Signed-off-by: Gilles Risch <gilles.risch@gmail.com>
> > > ---
> > >  drivers/gpu/drm/radeon/atombios_crtc.c     |  5 ++++-
> > >  drivers/gpu/drm/radeon/atombios_encoders.c | 11 ++++++-----
> > >  drivers/gpu/drm/radeon/radeon.h            |  1 +
> > >  3 files changed, 11 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/radeon/atombios_crtc.c b/drivers/gpu/drm/radeon/atombios_crtc.c
> > > index 2fc0334e0..075eba2d4 100644
> > > --- a/drivers/gpu/drm/radeon/atombios_crtc.c
> > > +++ b/drivers/gpu/drm/radeon/atombios_crtc.c
> > > @@ -24,6 +24,8 @@
> > >   *          Alex Deucher
> > >   */
> > >
> > > +#include <linux/dmi.h>
> > > +
> > >  #include <drm/drm_fixed.h>
> > >  #include <drm/drm_fourcc.h>
> > >  #include <drm/drm_framebuffer.h>
> > > @@ -594,7 +596,8 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
> > >                 if (((rdev->family == CHIP_RS780) || (rdev->family == CHIP_RS880))
> > >                     && !radeon_crtc->ss_enabled)
> > >                         radeon_crtc->pll_flags |= RADEON_PLL_USE_FRAC_FB_DIV;
> > > -               if (ASIC_IS_DCE32(rdev) && mode->clock > 165000)
> > > +               if ((ASIC_IS_DCE32(rdev) || dmi_match(DMI_PRODUCT_NAME, "iMac11,1"))
> > > +                   && mode->clock > 165000)
> > >                         radeon_crtc->pll_flags |= RADEON_PLL_USE_FRAC_FB_DIV;
> > >         } else {
> > >                 radeon_crtc->pll_flags |= RADEON_PLL_LEGACY;
> > > diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
> > > index 5cfd8fcfa..4de60559f 100644
> > > --- a/drivers/gpu/drm/radeon/atombios_encoders.c
> > > +++ b/drivers/gpu/drm/radeon/atombios_encoders.c
> > > @@ -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) || dmi_match(DMI_PRODUCT_NAME, "iMac11,1"))
> > >                                 atombios_dig_encoder_setup(encoder, ATOM_ENCODER_CMD_DP_VIDEO_ON, 0);
> > >                 }
> > >                 if (radeon_encoder->devices & (ATOM_DEVICE_LCD_SUPPORT)) {
> > > @@ -2123,12 +2123,13 @@ int radeon_atom_pick_dig_encoder(struct drm_encoder *encoder, int fe_idx)
> > >         }
> > >
> > >         /*
> > > -        * On DCE32 any encoder can drive any block so usually just use crtc id,
> > > -        * but Apple thinks different at least on iMac10,1 and iMac11,2, so there use linkb,
> > > -        * otherwise the internal eDP panel will stay dark.
> > > +        * On DCE31 and DCE32 any encoder can drive any block so usually just use crtc id,
> > > +        * but Apple thinks different at least on iMac10,1, iMac11,1 and iMac11,2,
> > > +        * so there use linkb, otherwise the internal eDP panel will stay dark.
> > >          */
> > > -       if (ASIC_IS_DCE32(rdev)) {
> > > +       if (ASIC_IS_DCE31(rdev)) {
> >
> > This will change the routing for DCE3.1 as well.  Probably best to do
> > something like:
> >
> > if (dmi_match(DMI_PRODUCT_NAME, "iMac11,1")) {
> >     enc_idx = (dig->linkb) ? 1 : 0;
> >     goto assigned;
> > }
> >
> > before or after the DCE32() block.
> >
> > >                 if (dmi_match(DMI_PRODUCT_NAME, "iMac10,1") ||
> > > +                   dmi_match(DMI_PRODUCT_NAME, "iMac11,1") ||
> > >                     dmi_match(DMI_PRODUCT_NAME, "iMac11,2"))
> > >                         enc_idx = (dig->linkb) ? 1 : 0;
> > >                 else
> > > diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
> > > index 527b9d19d..6b7c0abe4 100644
> > > --- a/drivers/gpu/drm/radeon/radeon.h
> > > +++ b/drivers/gpu/drm/radeon/radeon.h
> > > @@ -2625,6 +2625,7 @@ void r100_pll_errata_after_index(struct radeon_device *rdev);
> > >                             (rdev->family == CHIP_RS740)  ||    \
> > >                             (rdev->family >= CHIP_R600))
> > >  #define ASIC_IS_DCE3(rdev) ((rdev->family >= CHIP_RV620))
> > > +#define ASIC_IS_DCE31(rdev) ((rdev->family >= CHIP_RV770))
> > >  #define ASIC_IS_DCE32(rdev) ((rdev->family >= CHIP_RV730))
> > >  #define ASIC_IS_DCE4(rdev) ((rdev->family >= CHIP_CEDAR))
> > >  #define ASIC_IS_DCE41(rdev) ((rdev->family >= CHIP_PALM) && \
> > >
> > > base-commit: e7ae89a0c97ce2b68b0983cd01eda67cf373517d
> > > --
> > > 2.47.3
> > >
>
>
>
> --
> Gilles
>
> Sent from my Commodore C=64