drm/amd/display: use a more lax vblank enable policy for older ASICs

Ideally, we want to drop the legacy vblank enable for older ASICs. This
should be possible now, since we can now specify how many frames we need
to wait before disabling vblanking instead of being forced to either
choose between no delay (which can still be buggy) and
drm_vblank_offdelay (which is much longer by default than is required on
AMD hardware).

Suggested-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240822161856.174600-4-hamza.mahfooz@amd.com

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -8244,10 +8244,9 @@ static void manage_dm_interrupts(struct amdgpu_device *adev,
 
 	if (acrtc_state) {
 		if (amdgpu_ip_version(adev, DCE_HWIP, 0) <
-		    IP_VERSION(3, 5, 0)) {
-			drm_crtc_vblank_on(&acrtc->base);
-		} else if (acrtc_state->stream->link->psr_settings.psr_version <
-			   DC_PSR_VERSION_UNSUPPORTED) {
+		    IP_VERSION(3, 5, 0) ||
+		    acrtc_state->stream->link->psr_settings.psr_version <
+		    DC_PSR_VERSION_UNSUPPORTED) {
 			timing = &acrtc_state->stream->timing;
 
 			/* at least 2 frames */
@@ -8257,14 +8256,13 @@ static void manage_dm_interrupts(struct amdgpu_device *adev,
 						      timing->pix_clk_100hz);
 
 			config.offdelay_ms = offdelay ?: 30;
-			drm_crtc_vblank_on_config(&acrtc->base,
-						  &config);
 		} else {
 			config.disable_immediate = true;
-			drm_crtc_vblank_on_config(&acrtc->base,
-						  &config);
 		}
 
+		drm_crtc_vblank_on_config(&acrtc->base,
+					  &config);
+
 		amdgpu_irq_get(
 			adev,
 			&adev->pageflip_irq,