[Intel-gfx] [PATCH] Revert "drm/i915: Fix DP-MST crtc_mask"

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

This reverts commit 4eaceea3a00f8e936a7f48dcd0c975a57f88930f.

Several userspace clients (modesetting ddx and mutter+wayland at least)
handle encoder.possible_crtcs incorrectly. What they essentially do is
the following:

possible_crtcs = ~0;
for_each_possible_encoder(connector)
	possible_crtcs &= encoder->possible_crtcs;

Ie. they calculate the intersection of the possible_crtcs
for the connector when they really should be calculating the
union instead.

In our case each MST encoder now has just one unique bit set,
and so the intersection is always zero. The end result is that
MST connectors can't be lit up because no crtc can be found to
drive them.

I've submitted a fix for the modesetting ddx [1], and complained
on #wayland about mutter, so hopefully the situation will improve
in the future. In the meantime we have regression, and so must go
back to the old way of misconfiguring possible_crtcs in the kernel.

[1] https://gitlab.freedesktop.org/xorg/xserver/merge_requests/277

Cc: Jonas Ådahl <jadahl at gmail.com>
Cc: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111507
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_mst.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 6df240a01b8c..37366f81255b 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -615,7 +615,7 @@ intel_dp_create_fake_mst_encoder(struct intel_digital_port *intel_dig_port, enum
 	intel_encoder->type = INTEL_OUTPUT_DP_MST;
 	intel_encoder->power_domain = intel_dig_port->base.power_domain;
 	intel_encoder->port = intel_dig_port->base.port;
-	intel_encoder->crtc_mask = BIT(pipe);
+	intel_encoder->crtc_mask = 0x7;
 	intel_encoder->cloneable = 0;
 
 	intel_encoder->compute_config = intel_dp_mst_compute_config;
-- 
2.21.0