[PATCH v4 15/17] drm/i915/vrr: Pause DC Balancing for DSB commits

[Mitul Golani]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Pause the DMC DC Balancing for the remainder of the
commit so that vmin/vmax won't change after we've baked
them into the DSB vblank evasion commands.

--v2:
- Remove typo. (Ankit)
- Separate vrr enable structuring. (Ankit)

--v3:
- Add gaurd before accessing DC balance bits.
- Remove redundancy checks.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani at intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 17 +++++++++++++++++
 drivers/gpu/drm/i915/display/intel_vrr.c     |  9 +++++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 20c7c6eb485d..3111fd54968a 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7215,6 +7215,21 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
 	}
 
 	if (new_crtc_state->use_dsb) {
+		if (new_crtc_state->vrr.dc_balance.enable) {
+			/*
+			 * Pause the DMC DC balancing for the remainder of
+			 * the commit so that vmin/vmax won't change after
+			 * we've baked them into the DSB vblank evasion
+			 * commands.
+			 *
+			 * FIXME maybe need a small delay here to make sure
+			 * DMC has finished updating the values? Or we need
+			 * a better DMC<->driver protocol that gives is real
+			 * guarantees about that...
+			 */
+			intel_pipedmc_dcb_disable(NULL, crtc);
+		}
+
 		if (intel_crtc_needs_color_update(new_crtc_state))
 			intel_color_commit_noarm(new_crtc_state->dsb_commit,
 						 new_crtc_state);
@@ -7251,6 +7266,8 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
 			intel_vrr_send_push(new_crtc_state->dsb_commit, new_crtc_state);
 			intel_dsb_wait_vblank_delay(state, new_crtc_state->dsb_commit);
 			intel_vrr_check_push_sent(new_crtc_state->dsb_commit, new_crtc_state);
+			if (new_crtc_state->vrr.dc_balance.enable)
+				intel_pipedmc_dcb_enable(new_crtc_state->dsb_commit, crtc);
 			intel_dsb_interrupt(new_crtc_state->dsb_commit);
 		}
 	}
diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
index 92a1bd18fa7a..1275be16e749 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -9,6 +9,7 @@
 #include "i915_reg.h"
 #include "intel_de.h"
 #include "intel_display_types.h"
+#include "intel_dmc.h"
 #include "intel_dp.h"
 #include "intel_dmc_regs.h"
 #include "intel_vrr.h"
@@ -622,6 +623,7 @@ bool intel_vrr_always_use_vrr_tg(struct intel_display *display)
 void intel_vrr_enable(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_display *display = to_intel_display(crtc_state);
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
 	u32 ctl;
 
@@ -643,17 +645,24 @@ void intel_vrr_enable(const struct intel_crtc_state *crtc_state)
 		ctl |= VRR_CTL_CMRR_ENABLE;
 
 	intel_de_write(display, TRANS_VRR_CTL(display, cpu_transcoder), ctl);
+
+	if (crtc_state->vrr.dc_balance.enable)
+		intel_pipedmc_dcb_enable(NULL, crtc);
 }
 
 void intel_vrr_disable(const struct intel_crtc_state *old_crtc_state)
 {
 	struct intel_display *display = to_intel_display(old_crtc_state);
+	struct intel_crtc *crtc = to_intel_crtc(old_crtc_state->uapi.crtc);
 	enum transcoder cpu_transcoder = old_crtc_state->cpu_transcoder;
 	u32 ctl;
 
 	if (!old_crtc_state->vrr.enable)
 		return;
 
+	if (old_crtc_state->vrr.dc_balance.enable)
+		intel_pipedmc_dcb_disable(NULL, crtc);
+
 	ctl = trans_vrr_ctl(old_crtc_state);
 	if (intel_vrr_always_use_vrr_tg(display))
 		ctl |= VRR_CTL_VRR_ENABLE;
-- 
2.48.1