drm/i915/flipq: Implement flip queue based commit path

Support commits via the flip queue (as opposed to DSB or MMIO).

As it's somewhat unknown if we can actually use it is currently
gated behind the new use_flipq modparam, which defaults to disabled.

The implementation has a bunch of limitations that would need
real though to solve:
- disabled when PSR is used
- disabled when VRR is used
- color management updates not performed via the flip queue

v2: Don't use flip queue if there is no dmc
v3: Use intel_flipq_supported()
v3: Configure PKG_C_LATENCY appropriately
    Ignore INT_VECTOR if there is a real PIPEDMC interrupt
    (nothing in the hw appears to clear INT_VECTOR)
v4: Leave added_wake_time=0 when flip queue isn't used, to
    avoid needleslly increasing pkg_c_latency on lnl/ptl due
    to Wa_22020432604. This is a bit racy though...
    Use IS_DISPLAY_VER()

Reviewed-by: Uma Shankar <[email protected]>
Signed-off-by: Ville Syrjälä <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: vsyrjala

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

@@ -93,6 +93,7 @@
 #include "intel_fbc.h"
 #include "intel_fdi.h"
 #include "intel_fifo_underrun.h"
+#include "intel_flipq.h"
 #include "intel_frontbuffer.h"
 #include "intel_hdmi.h"
 #include "intel_hotplug.h"
@@ -6619,7 +6620,7 @@ static void commit_pipe_pre_planes(struct intel_atomic_state *state,
 		intel_atomic_get_new_crtc_state(state, crtc);
 	bool modeset = intel_crtc_needs_modeset(new_crtc_state);
 
-	drm_WARN_ON(display->drm, new_crtc_state->use_dsb);
+	drm_WARN_ON(display->drm, new_crtc_state->use_dsb || new_crtc_state->use_flipq);
 
 	/*
 	 * During modesets pipe configuration was programmed as the
@@ -6649,7 +6650,7 @@ static void commit_pipe_post_planes(struct intel_atomic_state *state,
 		intel_atomic_get_new_crtc_state(state, crtc);
 	bool modeset = intel_crtc_needs_modeset(new_crtc_state);
 
-	drm_WARN_ON(display->drm, new_crtc_state->use_dsb);
+	drm_WARN_ON(display->drm, new_crtc_state->use_dsb || new_crtc_state->use_flipq);
 
 	/*
 	 * Disable the scaler(s) after the plane(s) so that we don't
@@ -6738,10 +6739,10 @@ static void intel_pre_update_crtc(struct intel_atomic_state *state,
 
 	if (!modeset &&
 	    intel_crtc_needs_color_update(new_crtc_state) &&
-	    !new_crtc_state->use_dsb)
+	    !new_crtc_state->use_dsb && !new_crtc_state->use_flipq)
 		intel_color_commit_noarm(NULL, new_crtc_state);
 
-	if (!new_crtc_state->use_dsb)
+	if (!new_crtc_state->use_dsb && !new_crtc_state->use_flipq)
 		intel_crtc_planes_update_noarm(NULL, state, crtc);
 }
 
@@ -6753,7 +6754,14 @@ static void intel_update_crtc(struct intel_atomic_state *state,
 	struct intel_crtc_state *new_crtc_state =
 		intel_atomic_get_new_crtc_state(state, crtc);
 
-	if (new_crtc_state->use_dsb) {
+	if (new_crtc_state->use_flipq) {
+		intel_flipq_enable(new_crtc_state);
+
+		intel_crtc_prepare_vblank_event(new_crtc_state, &crtc->flipq_event);
+
+		intel_flipq_add(crtc, INTEL_FLIPQ_PLANE_1, 0, INTEL_DSB_0,
+				new_crtc_state->dsb_commit);
+	} else if (new_crtc_state->use_dsb) {
 		intel_crtc_prepare_vblank_event(new_crtc_state, &crtc->dsb_event);
 
 		intel_dsb_commit(new_crtc_state->dsb_commit);
@@ -7191,7 +7199,17 @@ static void intel_atomic_dsb_prepare(struct intel_atomic_state *state,
 		return;
 
 	/* FIXME deal with everything */
+	new_crtc_state->use_flipq =
+		intel_flipq_supported(display) &&
+		!new_crtc_state->do_async_flip &&
+		!new_crtc_state->vrr.enable &&
+		!new_crtc_state->has_psr &&
+		!intel_crtc_needs_modeset(new_crtc_state) &&
+		!intel_crtc_needs_fastset(new_crtc_state) &&
+		!intel_crtc_needs_color_update(new_crtc_state);
+
 	new_crtc_state->use_dsb =
+		!new_crtc_state->use_flipq &&
 		!new_crtc_state->do_async_flip &&
 		(DISPLAY_VER(display) >= 20 || !new_crtc_state->has_psr) &&
 		!intel_crtc_needs_modeset(new_crtc_state) &&
@@ -7207,7 +7225,9 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
 	struct intel_crtc_state *new_crtc_state =
 		intel_atomic_get_new_crtc_state(state, crtc);
 
-	if (!new_crtc_state->use_dsb && !new_crtc_state->dsb_color)
+	if (!new_crtc_state->use_flipq &&
+	    !new_crtc_state->use_dsb &&
+	    !new_crtc_state->dsb_color)
 		return;
 
 	/*
@@ -7216,14 +7236,16 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
 	 * Double that for pipe stuff and other overhead.
 	 */
 	new_crtc_state->dsb_commit = intel_dsb_prepare(state, crtc, INTEL_DSB_0,
-						       new_crtc_state->use_dsb ? 1024 : 16);
+						       new_crtc_state->use_dsb ||
+						       new_crtc_state->use_flipq ? 1024 : 16);
 	if (!new_crtc_state->dsb_commit) {
+		new_crtc_state->use_flipq = false;
 		new_crtc_state->use_dsb = false;
 		intel_color_cleanup_commit(new_crtc_state);
 		return;
 	}
 
-	if (new_crtc_state->use_dsb) {
+	if (new_crtc_state->use_flipq || new_crtc_state->use_dsb) {
 		if (intel_crtc_needs_color_update(new_crtc_state))
 			intel_color_commit_noarm(new_crtc_state->dsb_commit,
 						 new_crtc_state);
@@ -7238,7 +7260,8 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
 		intel_psr_trigger_frame_change_event(new_crtc_state->dsb_commit,
 						     state, crtc);
 
-		intel_dsb_vblank_evade(state, new_crtc_state->dsb_commit);
+		if (new_crtc_state->use_dsb)
+			intel_dsb_vblank_evade(state, new_crtc_state->dsb_commit);
 
 		if (intel_crtc_needs_color_update(new_crtc_state))
 			intel_color_commit_arm(new_crtc_state->dsb_commit,
@@ -7417,6 +7440,9 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
 
 		if (!state->base.legacy_cursor_update && !new_crtc_state->use_dsb)
 			intel_vrr_check_push_sent(NULL, new_crtc_state);
+
+		if (new_crtc_state->use_flipq)
+			intel_flipq_disable(new_crtc_state);
 	}
 
 	/*

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

@@ -62,6 +62,9 @@ intel_display_param_named_unsafe(enable_dpt, bool, 0400,
 intel_display_param_named_unsafe(enable_dsb, bool, 0400,
 	"Enable display state buffer (DSB) (default: true)");
 
+intel_display_param_named_unsafe(enable_flipq, bool, 0400,
+	"Enable DMC flip queue (default: false)");
+
 intel_display_param_named_unsafe(enable_sagv, bool, 0400,
 	"Enable system agent voltage/frequency scaling (SAGV) (default: true)");
 

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

@@ -31,6 +31,7 @@ struct drm_printer;
 	param(int, enable_dc, -1, 0400) \
 	param(bool, enable_dpt, true, 0400) \
 	param(bool, enable_dsb, true, 0600) \
+	param(bool, enable_flipq, false, 0600) \
 	param(bool, enable_sagv, true, 0600) \
 	param(int, disable_power_well, -1, 0400) \
 	param(bool, enable_ips, true, 0600) \

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

@@ -1305,6 +1305,7 @@ struct intel_crtc_state {
 	/* For DSB based pipe updates */
 	struct intel_dsb *dsb_color, *dsb_commit;
 	bool use_dsb;
+	bool use_flipq;
 
 	u32 psr2_man_track_ctl;
 
@@ -1412,6 +1413,8 @@ struct intel_crtc {
 	struct drm_pending_vblank_event *flip_done_event;
 	/* armed event for DSB based updates */
 	struct drm_pending_vblank_event *dsb_event;
+	/* armed event for flip queue based updates */
+	struct drm_pending_vblank_event *flipq_event;
 
 	/* Access to these should be protected by display->irq.lock. */
 	bool cpu_fifo_underrun_disabled;

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

@@ -501,7 +501,8 @@ static u32 pipedmc_interrupt_mask(struct intel_display *display)
 	 * triggering it during the first DC state transition. Figure
 	 * out what is going on...
 	 */
-	return PIPEDMC_GTT_FAULT |
+	return PIPEDMC_FLIPQ_PROG_DONE |
+		PIPEDMC_GTT_FAULT |
 		PIPEDMC_ATS_FAULT;
 }
 
@@ -1608,12 +1609,29 @@ void intel_dmc_debugfs_register(struct intel_display *display)
 void intel_pipedmc_irq_handler(struct intel_display *display, enum pipe pipe)
 {
 	struct intel_crtc *crtc = intel_crtc_for_pipe(display, pipe);
-	u32 tmp;
+	u32 tmp = 0, int_vector;
 
 	if (DISPLAY_VER(display) >= 20) {
 		tmp = intel_de_read(display, PIPEDMC_INTERRUPT(pipe));
 		intel_de_write(display, PIPEDMC_INTERRUPT(pipe), tmp);
 
+		if (tmp & PIPEDMC_FLIPQ_PROG_DONE) {
+			spin_lock(&display->drm->event_lock);
+
+			if (crtc->flipq_event) {
+				/*
+				 * Update vblank counter/timestamp in case it
+				 * hasn't been done yet for this frame.
+				 */
+				drm_crtc_accurate_vblank_count(&crtc->base);
+
+				drm_crtc_send_vblank_event(&crtc->base, crtc->flipq_event);
+				crtc->flipq_event = NULL;
+			}
+
+			spin_unlock(&display->drm->event_lock);
+		}
+
 		if (tmp & PIPEDMC_ATS_FAULT)
 			drm_err_ratelimited(display->drm, "[CRTC:%d:%s] PIPEDMC ATS fault\n",
 					    crtc->base.base.id, crtc->base.name);
@@ -1625,8 +1643,8 @@ void intel_pipedmc_irq_handler(struct intel_display *display, enum pipe pipe)
 				crtc->base.base.id, crtc->base.name);
 	}
 
-	tmp = intel_de_read(display, PIPEDMC_STATUS(pipe)) & PIPEDMC_INT_VECTOR_MASK;
-	if (tmp)
+	int_vector = intel_de_read(display, PIPEDMC_STATUS(pipe)) & PIPEDMC_INT_VECTOR_MASK;
+	if (tmp == 0 && int_vector != 0)
 		drm_err(display->drm, "[CRTC:%d:%s]] PIPEDMC interrupt vector 0x%x\n",
 			crtc->base.base.id, crtc->base.name, tmp);
 }

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

@@ -112,6 +112,9 @@ static void intel_flipq_crtc_init(struct intel_crtc *crtc)
 
 bool intel_flipq_supported(struct intel_display *display)
 {
+	if (!display->params.enable_flipq)
+		return false;
+
 	if (!display->dmc.dmc)
 		return false;
 
@@ -140,7 +143,7 @@ static int cdclk_factor(struct intel_display *display)
 		return 280;
 }
 
-static int intel_flipq_exec_time_us(struct intel_display *display)
+int intel_flipq_exec_time_us(struct intel_display *display)
 {
 	return intel_dsb_exec_time_us() +
 		DIV_ROUND_UP(display->cdclk.hw.cdclk * cdclk_factor(display), 540000) +

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

@@ -28,5 +28,6 @@ void intel_flipq_add(struct intel_crtc *crtc,
 		     unsigned int pts,
 		     enum intel_dsb_id dsb_id,
 		     struct intel_dsb *dsb);
+int intel_flipq_exec_time_us(struct intel_display *display);
 
 #endif /* __INTEL_FLIPQ_H__ */

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

@@ -26,6 +26,7 @@
 #include "intel_display_types.h"
 #include "intel_fb.h"
 #include "intel_fixed.h"
+#include "intel_flipq.h"
 #include "intel_pcode.h"
 #include "intel_plane.h"
 #include "intel_wm.h"
@@ -2897,11 +2898,15 @@ intel_program_dpkgc_latency(struct intel_atomic_state *state)
 
 	latency = skl_watermark_max_latency(display, 1);
 
+	/* FIXME runtime changes to enable_flipq are racy */
+	if (display->params.enable_flipq)
+		added_wake_time = intel_flipq_exec_time_us(display);
+
 	/*
 	 * Wa_22020432604
 	 * "PKG_C_LATENCY Added Wake Time field is not working"
 	 */
-	if (latency && (DISPLAY_VER(display) == 20 || DISPLAY_VER(display) == 30)) {
+	if (latency && IS_DISPLAY_VER(display, 20, 30)) {
 		latency += added_wake_time;
 		added_wake_time = 0;
 	}