On Thu, May 28, 2026 at 3:39 AM Gilles Risch <[email protected]> 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 <[email protected]>
> ---
> 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
>
