drm/i915/vrr: Pause DC Balancing for DSB commits

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.

--v4:
- Move events to separate function.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patch.msgid.link/20251223104542.2688548-17-mitulkumar.ajitkumar.golani@intel.com

2 files changed, 22 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 68e67dc2631f..039cf34b8f12 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7330,6 +7330,21 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
 		if (new_crtc_state->use_flipq)
 			intel_flipq_wait_dmc_halt(new_crtc_state->dsb_commit, crtc);
 
+		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);
@@ -7383,6 +7398,10 @@ static void intel_atomic_dsb_finish(struct intel_atomic_state *state,
 		intel_dsb_wait_for_delayed_vblank(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 a4a198a28519..ac612cf08d98 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -10,6 +10,7 @@
 #include "intel_de.h"
 #include "intel_display_regs.h"
 #include "intel_display_types.h"
+#include "intel_dmc.h"
 #include "intel_dmc_regs.h"
 #include "intel_dp.h"
 #include "intel_psr.h"
@@ -824,6 +825,7 @@ intel_vrr_enable_dc_balancing(const struct intel_crtc_state *crtc_state)
 		       crtc_state->vrr.dc_balance.vblank_target);
 	intel_de_write(display, TRANS_ADAPTIVE_SYNC_DCB_CTL(cpu_transcoder),
 		       ADAPTIVE_SYNC_COUNTER_EN);
+	intel_pipedmc_dcb_enable(NULL, crtc);
 }
 
 static void
@@ -837,6 +839,7 @@ intel_vrr_disable_dc_balancing(const struct intel_crtc_state *old_crtc_state)
 	if (!old_crtc_state->vrr.dc_balance.enable)
 		return;
 
+	intel_pipedmc_dcb_disable(NULL, crtc);
 	intel_de_write(display, TRANS_ADAPTIVE_SYNC_DCB_CTL(cpu_transcoder), 0);
 	intel_de_write(display, PIPEDMC_DCB_VMIN(pipe), 0);
 	intel_de_write(display, PIPEDMC_DCB_VMAX(pipe), 0);