drm/i915/dsb: Introduce intel_dsb_wait_vblanks()

Add a function to emit a DSB wait for vblank instruction. This
just waits until the specified number of vblanks.

Note that this triggers on the transcoder's undelayed vblank,
as opposed to the pipe's delayed vblank.

Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-8-ville.syrjala@linux.intel.com

Author: vsyrjala

drivers/gpu/drm/i915/display/intel_dsb.c

@@ -399,6 +399,12 @@ void intel_dsb_wait_usec(struct intel_dsb *dsb, int count)
 		       DSB_OPCODE_WAIT_USEC << DSB_OPCODE_SHIFT);
 }
 
+void intel_dsb_wait_vblanks(struct intel_dsb *dsb, int count)
+{
+	intel_dsb_emit(dsb, count,
+		       DSB_OPCODE_WAIT_VBLANKS << DSB_OPCODE_SHIFT);
+}
+
 static void intel_dsb_emit_wait_dsl(struct intel_dsb *dsb,
 				    u32 opcode, int lower, int upper)
 {

drivers/gpu/drm/i915/display/intel_dsb.h

@@ -41,6 +41,7 @@ void intel_dsb_nonpost_start(struct intel_dsb *dsb);
 void intel_dsb_nonpost_end(struct intel_dsb *dsb);
 void intel_dsb_interrupt(struct intel_dsb *dsb);
 void intel_dsb_wait_usec(struct intel_dsb *dsb, int count);
+void intel_dsb_wait_vblanks(struct intel_dsb *dsb, int count);
 void intel_dsb_wait_scanline_in(struct intel_atomic_state *state,
 				struct intel_dsb *dsb,
 				int lower, int upper);