Allow/Fix use of multiple ZaphodHead outputs per x-screen. (v2)

Defining multiple ZaphodHead outputs per x-screen in a
multiple x-screen's per gpu configuration caused all
outputs except one per x-screen to go dark, because
there was a fixed mapping x-screen number -> crtc number,
limiting the number of crtc's per x-screen to one.

On a ZaphodHead's setup, be more clever and assign
as many crtc's to a given x-screen as there are
ZaphodHeads defined for that screen, assuming
there are enough unused crtc's available.

Tested on a triple display setup with different combos
of one, two or three ZaphodHeads per one, two or three
x-screens.

This is a port of similar code from xf86-video-nouveau.

v2: Implement suggestions by Michel Dänzer: Less verbose
    debug output, more clear warning message on crtc allocation
    failure. Move clearing of per gpu assigned_crtc mask to
    CloseScreen, indeed testing shows no need for the more
    complex new server generation check from v1.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
(v1) Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/radeon_probe.h b/src/radeon_probe.h
index 3fe4644c..958cb23b 100644
--- a/src/radeon_probe.h
+++ b/src/radeon_probe.h
@@ -142,6 +142,7 @@ typedef struct
     int fd_ref;
     unsigned long     fd_wakeup_registered; /* server generation for which fd has been registered for wakeup handling */
     int fd_wakeup_ref;
+    unsigned int assigned_crtcs;
 #ifdef XSERVER_PLATFORM_BUS
     struct xf86_platform_device *platform_dev;
 #endif