backend/drm: try to allocate crtc for formats
backend/drm: try to allocate crtc for formats

To retrieve the formats, an allocated crtc is required. If there is no
currently no crtc available, try to allocate it. This reproducable by
having a disabled output and going through a suspend cycle with amdgpu.
On start CRTCs look like this:

  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1099] Reallocating CRTCs
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1110] State before reallocation:
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'DP-1' crtc=0 state=1 desired_enabled=1
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'DP-2' crtc=1 state=1 desired_enabled=1
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'HDMI-A-1' crtc=-1 state=0 desired_enabled=0
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'HDMI-A-2' crtc=-1 state=0 desired_enabled=0
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'DVI-D-1' crtc=-1 state=0 desired_enabled=0
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1167] State after reallocation:
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'DP-1' crtc=0 state=1 desired_enabled=1
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'DP-2' crtc=1 state=1 desired_enabled=1
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'HDMI-A-1' crtc=-1 state=0 desired_enabled=0
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'HDMI-A-2' crtc=-1 state=0 desired_enabled=0
  00:00:00.588 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'DVI-D-1' crtc=-1 state=0 desired_enabled=0

where DP-1 is than disabled. After suspend/resume, allocation turns into:

  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1099] Reallocating CRTCs
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1110] State before reallocation:
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'DP-1' crtc=-1 state=1 desired_enabled=0
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'DP-2' crtc=1 state=3 desired_enabled=1
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'HDMI-A-1' crtc=-1 state=0 desired_enabled=0
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'HDMI-A-2' crtc=-1 state=0 desired_enabled=0
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1116]   'DVI-D-1' crtc=-1 state=0 desired_enabled=0
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1167] State after reallocation:
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'DP-1' crtc=-1 state=1 desired_enabled=0
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'DP-2' crtc=1 state=3 desired_enabled=1
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'HDMI-A-1' crtc=-1 state=0 desired_enabled=0
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'HDMI-A-2' crtc=-1 state=0 desired_enabled=0
  00:30:22.680 [DEBUG] [wlr] [backend/drm/drm.c:1174]   'DVI-D-1' crtc=-1 state=0 desired_enabled=0

where the crtc for DP-1 is now NULL. Trying to enable the output results
in:

  10:43:36.906 [DEBUG] [sway/config/output.c:351] Turning on output DP-1
  10:43:36.906 [DEBUG] [sway/config/output.c:360] Set preferred mode
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [sway/config/output.c:366] Preferred mode rejected, falling back to another mode
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.906 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.906 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.906 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [DEBUG] [sway/config/output.c:400] Auto-detected output scale: 1.000000
  10:43:36.907 [DEBUG] [sway/config/output.c:430] Committing output DP-1
  10:43:36.907 [DEBUG] [wlr] [backend/drm/drm.c:464] connector DP-1: Can't enable an output without a buffer
  10:43:36.907 [DEBUG] [wlr] [types/wlr_output.c:689] Attaching empty buffer to output for modeset
  10:43:36.907 [ERROR] [wlr] [types/wlr_output.c:512] Failed to get primary display formats
  10:43:36.907 [ERROR] [sway/config/output.c:435] Failed to commit output DP-1

where the primary format can't be queried since there is no crtc
allocated for the connector. Allocating the connector inside
drm_connector_get_primary_formats() fixes this issue. This is possible
since the only user of get_primary_formats() is the swapchain allocation
function, which is only called on output enable. Do the same thing for
the cursor formats in case the user queries them before the output is
enabled.

swaywm/wlroots,swaywm/wlroots,SirCmpwn/wlroots