[PATCH 4/5] drm/i915/cursor: Program secondary cursor planes

[Nemesa Garg <nemesa.garg@intel.com>]

Iterate over all joined pipes when arming/disabling the cursor plane so
secondary pipes are updated together with the primary. The pin, check
and state duplication for secondary pipes was already prepared in the
previous commit; this converts the update_arm pass to a loop over the
joined_pipe_state[] array.

Because the whole loop runs inside a single primary vblank-evade,
sample intel_crtc_get_vblank_counter() per pipe around each arm and
emit a drm_err() if the counter ticks during that pipe's own
programming.

v2: Check primary and secondary pipe together. [Ville]
v3: Use struct intel_cursor_joiner_state. [Ville]
v4: Add per-pipe vblank straddle detection around the arm loop. [Chaitanya]
v5: Move straddle check outside the loop to cover all pipes together.
    Sample vblank counter from primary pipe only.
    Move drm_err() after local_irq_enable(). [Chaitanya]

Assisted-by: Claude:claude-sonnet-4.6
Signed-off-by: Nemesa Garg <nemesa.garg@intel.com>
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
---
 drivers/gpu/drm/i915/display/intel_cursor.c | 36 +++++++++++++++++----
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index b4f0f70eaa1a..894bd1df5f42 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -13,6 +13,7 @@
 #include <drm/drm_vblank.h>
 
 #include "intel_atomic.h"
+#include "intel_crtc.h"
 #include "intel_cursor.h"
 #include "intel_cursor_regs.h"
 #include "intel_de.h"
@@ -904,6 +905,7 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 	struct intel_cursor_joiner_state joined_pipe_state[I915_MAX_PIPES] = {};
 	struct intel_crtc *pipe_crtc;
 	int num_pipes = 0;
+	u32 start_vbl_count, end_vbl_count;
 	int ret;
 
 	/*
@@ -1049,17 +1051,37 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		local_irq_disable();
 	}
 
-	if (joined_pipe_state[0].new_plane_state->uapi.visible) {
-		intel_plane_update_noarm(NULL, plane, crtc_state,
-					 joined_pipe_state[0].new_plane_state);
-		intel_plane_update_arm(NULL, plane, crtc_state,
-				       joined_pipe_state[0].new_plane_state);
-	} else {
-		intel_plane_disable_arm(NULL, plane, crtc_state);
+	/*
+	 * Joiner pipes are vblank-synchronized, so sampling only the primary
+	 * pipe is sufficient to detect a straddle across all joined pipes.
+	 * The vblank evasion above also operates on the primary pipe only.
+	 */
+	start_vbl_count = intel_crtc_get_vblank_counter(joined_pipe_state[0].crtc);
+
+	for (int i = 0; i < num_pipes; i++) {
+		if (joined_pipe_state[i].new_plane_state->uapi.visible) {
+			intel_plane_update_noarm(NULL, joined_pipe_state[i].plane,
+						 joined_pipe_state[i].crtc_state,
+						 joined_pipe_state[i].new_plane_state);
+			intel_plane_update_arm(NULL, joined_pipe_state[i].plane,
+					       joined_pipe_state[i].crtc_state,
+					       joined_pipe_state[i].new_plane_state);
+		} else {
+			intel_plane_disable_arm(NULL, joined_pipe_state[i].plane,
+						joined_pipe_state[i].crtc_state);
+		}
 	}
 
+	end_vbl_count = intel_crtc_get_vblank_counter(joined_pipe_state[0].crtc);
+
 	local_irq_enable();
 
+	if (start_vbl_count != end_vbl_count)
+		drm_err(display->drm,
+			"Atomic update failure on pipe %c (start=%u end=%u)\n",
+			pipe_name(joined_pipe_state[0].crtc->pipe),
+			start_vbl_count, end_vbl_count);
+
 	intel_psr_unlock(crtc_state);
 
 	/*
-- 
2.25.1