The late 2009, 27 inch Apple iMac10,1 has an internal eDP display and an external Mini- Displayport output, driven by a DCE-3.2, RV730 Radeon Mobility HD-4670. The machine worked fine in a dual-display setup with eDP panel + externally connected HDMI or DVI-D digital display sink, connected via MiniDP to DVI or HDMI adapter. However, booting the machine single-display with only eDP panel results in a completely black display - even backlight powering off, as soon as the radeon modesetting driver loads. This patch fixes the single dispay eDP case by assigning encoders based on dig->linkb, similar to DCE-4+. While this should not be generally necessary (Alex: "...atom on normal boards should be able to handle any mapping."), Apple seems to use some special routing here. One remaining problem not solved by this patch is that an external Minidisplayport->DP sink does still not work on iMac10,1, whereas external DVI and HDMI sinks continue to work. The problem affects at least all tested kernels since Linux 3.13 - didn't test earlier kernels, so backporting to stable probably makes sense. v2: With the original patch from 2016, Alex was worried it will break other DCE3.2 systems. Use dmi_match() to apply this special encoder assignment only for the Apple iMac 10,1 from late 2009. Signed-off-by: Mario Kleiner <mario.kleiner.de@xxxxxxxxx> Cc: Alex Deucher <alexander.deucher@xxxxxxx> Cc: Michel Dänzer <michel.daenzer@xxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/radeon/atombios_encoders.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c index fa4f8f0..e67ed38 100644 --- a/drivers/gpu/drm/radeon/atombios_encoders.c +++ b/drivers/gpu/drm/radeon/atombios_encoders.c @@ -31,6 +31,7 @@ #include "radeon_asic.h" #include "atom.h" #include <linux/backlight.h> +#include <linux/dmi.h> extern int atom_debug; @@ -2184,9 +2185,17 @@ int radeon_atom_pick_dig_encoder(struct drm_encoder *encoder, int fe_idx) goto assigned; } - /* on DCE32 and encoder can driver any block so just crtc id */ + /* + * 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)) { - enc_idx = radeon_crtc->crtc_id; + if (dmi_match(DMI_PRODUCT_NAME, "iMac10,1")) + enc_idx = (dig->linkb) ? 1 : 0; + else + enc_idx = radeon_crtc->crtc_id; + goto assigned; } -- 2.7.4