drm/i915: use display snapshot mechanism for display irq regs

Move more display specific parts of GPU error logging behind the display
snapshot interface.

With the display register capture reduced to just one register, DERRMR,
there's quite a bit of boilerplate here. However, it's still a nice
abstraction and removes a DISPLAY_VER() usage from core i915. With this
approach, it's also easy to add to xe as needed.

v2: Remove stale comment

Reviewed-by: Ville Syrjälä <[e-mail]>
Link: https://lore.kernel.org/r/132[e-mail]
Signed-off-by: Jani Nikula <[e-mail]>

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

···
 
 	INIT_WORK(&display->irq.vblank_dc_work, intel_display_vblank_dc_work);
 }
+
+struct intel_display_irq_snapshot {
+	u32 derrmr;
+};
+
+struct intel_display_irq_snapshot *
+intel_display_irq_snapshot_capture(struct intel_display *display)
+{
+	struct intel_display_irq_snapshot *snapshot;
+
+	snapshot = kzalloc(sizeof(*snapshot), GFP_ATOMIC);
+	if (!snapshot)
+		return NULL;
+
+	if (DISPLAY_VER(display) >= 6 && DISPLAY_VER(display) < 20)
+		snapshot->derrmr = intel_de_read(display, DERRMR);
+
+	return snapshot;
+}
+
+void intel_display_irq_snapshot_print(const struct intel_display_irq_snapshot *snapshot,
+				      struct drm_printer *p)
+{
+	if (!snapshot)
+		return;
+
+	drm_printf(p, "DERRMR: 0x%08x\n", snapshot->derrmr);
+}

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

···
 
 enum pipe;
 struct drm_crtc;
+struct drm_printer;
 struct intel_display;
+struct intel_display_irq_snapshot;
 
 void valleyview_enable_display_irqs(struct intel_display *display);
 void valleyview_disable_display_irqs(struct intel_display *display);
···
 void intel_display_irq_init(struct intel_display *display);
 
 void i915gm_irq_cstate_wa(struct intel_display *display, bool enable);
+
+struct intel_display_irq_snapshot *intel_display_irq_snapshot_capture(struct intel_display *display);
+void intel_display_irq_snapshot_print(const struct intel_display_irq_snapshot *snapshot, struct drm_printer *p);
 
 #endif /* __INTEL_DISPLAY_IRQ_H__ */

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

···
 
 #include "intel_display_core.h"
 #include "intel_display_device.h"
+#include "intel_display_irq.h"
 #include "intel_display_params.h"
 #include "intel_display_snapshot.h"
 #include "intel_dmc.h"
···
 	struct intel_display_params params;
 	struct intel_overlay_snapshot *overlay;
 	struct intel_dmc_snapshot *dmc;
+	struct intel_display_irq_snapshot *irq;
 };
 
 struct intel_display_snapshot *intel_display_snapshot_capture(struct intel_display *display)
···
 
 	intel_display_params_copy(&snapshot->params);
 
+	snapshot->irq = intel_display_irq_snapshot_capture(display);
 	snapshot->overlay = intel_overlay_snapshot_capture(display);
 	snapshot->dmc = intel_dmc_snapshot_capture(display);
 
···
 	intel_display_device_info_print(&snapshot->info, &snapshot->runtime_info, p);
 	intel_display_params_dump(&snapshot->params, display->drm->driver->name, p);
 
+	intel_display_irq_snapshot_print(snapshot->irq, p);
 	intel_overlay_snapshot_print(snapshot->overlay, p);
 	intel_dmc_snapshot_print(snapshot->dmc, p);
 }
···
 
 	intel_display_params_free(&snapshot->params);
 
+	kfree(snapshot->irq);
 	kfree(snapshot->overlay);
 	kfree(snapshot->dmc);
 	kfree(snapshot);

drivers/gpu/drm/i915/i915_gpu_error.c

···
 	intel_sseu_print_topology(gt->_gt->i915, &gt->info.sseu, &p);
 }
 
-static void err_print_gt_display(struct drm_i915_error_state_buf *m,
-				 struct intel_gt_coredump *gt)
-{
-	err_printf(m, "DERRMR: 0x%08x\n", gt->derrmr);
-}
-
 static void err_print_gt_global_nonguc(struct drm_i915_error_state_buf *m,
 				       struct intel_gt_coredump *gt)
 {
···
 		if (error->gt->uc && error->gt->uc->guc.is_guc_capture)
 			print_guc_capture = true;
 
-		err_print_gt_display(m, error->gt);
 		err_print_gt_global_nonguc(m, error->gt);
 		err_print_gt_fences(m, error->gt);
 
···
 	return error_uc;
 }
 
-/* Capture display registers. */
-static void gt_record_display_regs(struct intel_gt_coredump *gt)
-{
-	struct intel_uncore *uncore = gt->_gt->uncore;
-	struct drm_i915_private *i915 = uncore->i915;
-
-	if (DISPLAY_VER(i915) >= 6 && DISPLAY_VER(i915) < 20)
-		gt->derrmr = intel_uncore_read(uncore, DERRMR);
-}
-
 /* Capture all other registers that GuC doesn't capture. */
 static void gt_record_global_nonguc_regs(struct intel_gt_coredump *gt)
 {
···
 	gc->_gt = gt;
 	gc->awake = intel_gt_pm_is_awake(gt);
 
-	gt_record_display_regs(gc);
 	gt_record_global_nonguc_regs(gc);
 
 	/*

drivers/gpu/drm/i915/i915_gpu_error.h

···
 	u32 clock_frequency;
 	u32 clock_period_ns;
 
-	/* Display related */
-	u32 derrmr;
 	u32 sfc_done[I915_MAX_SFC]; /* gen12 */
 
 	u32 nfence;