drm/i915/fbc: Decouple FBC from intel_cdclk_atomic_check()

Always account for FBC requirements in intel_crtc_compute_min_cdclk()
so that we don't have to worry about the actual CDCLK frequency in
intel_fbc_check_plane() any longer.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20251013201236.30084-6-ville.syrjala@linux.intel.com
Reviewed-by: Mika Kahola <mika.kahola@intel.com>

3 files changed, 38 insertions, 13 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index 0cef55b56b86..8fb19e605832 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -2842,6 +2842,7 @@ static int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_stat
 
 	min_cdclk = intel_pixel_rate_to_cdclk(crtc_state);
 	min_cdclk = max(min_cdclk, intel_crtc_bw_min_cdclk(crtc_state));
+	min_cdclk = max(min_cdclk, intel_fbc_min_cdclk(crtc_state));
 	min_cdclk = max(min_cdclk, hsw_ips_min_cdclk(crtc_state));
 	min_cdclk = max(min_cdclk, intel_audio_min_cdclk(crtc_state));
 	min_cdclk = max(min_cdclk, vlv_dsi_min_cdclk(crtc_state));
diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 83903bb696ff..10ef3136dadc 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -53,7 +53,6 @@
 #include "i915_vgpu.h"
 #include "i915_vma.h"
 #include "i9xx_plane_regs.h"
-#include "intel_cdclk.h"
 #include "intel_de.h"
 #include "intel_display_device.h"
 #include "intel_display_regs.h"
@@ -1420,6 +1419,18 @@ intel_fbc_prepare_dirty_rect(struct intel_atomic_state *state,
 	}
 }
 
+static int _intel_fbc_min_cdclk(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_display *display = to_intel_display(crtc_state);
+
+	/* WaFbcExceedCdClockThreshold:hsw,bdw */
+	if (display->platform.haswell || display->platform.broadwell)
+		return DIV_ROUND_UP(crtc_state->pixel_rate * 100, 95);
+
+	/* no FBC specific limits to worry about */
+	return 0;
+}
+
 static int intel_fbc_check_plane(struct intel_atomic_state *state,
 				 struct intel_plane *plane)
 {
@@ -1559,18 +1570,9 @@ static int intel_fbc_check_plane(struct intel_atomic_state *state,
 		return 0;
 	}
 
-	/* WaFbcExceedCdClockThreshold:hsw,bdw */
-	if (display->platform.haswell || display->platform.broadwell) {
-		const struct intel_cdclk_state *cdclk_state;
-
-		cdclk_state = intel_atomic_get_cdclk_state(state);
-		if (IS_ERR(cdclk_state))
-			return PTR_ERR(cdclk_state);
-
-		if (crtc_state->pixel_rate >= intel_cdclk_logical(cdclk_state) * 95 / 100) {
-			plane_state->no_fbc_reason = "pixel rate too high";
-			return 0;
-		}
+	if (_intel_fbc_min_cdclk(crtc_state) > display->cdclk.max_cdclk_freq) {
+		plane_state->no_fbc_reason = "pixel rate too high";
+		return 0;
 	}
 
 	plane_state->no_fbc_reason = NULL;
@@ -1578,6 +1580,27 @@ static int intel_fbc_check_plane(struct intel_atomic_state *state,
 	return 0;
 }
 
+int intel_fbc_min_cdclk(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);
+	struct intel_plane *plane = to_intel_plane(crtc->base.primary);
+	int min_cdclk;
+
+	if (!plane->fbc)
+		return 0;
+
+	min_cdclk = _intel_fbc_min_cdclk(crtc_state);
+
+	/*
+	 * Do not ask for more than the max CDCLK frequency,
+	 * if that is not enough FBC will simply not be used.
+	 */
+	if (min_cdclk > display->cdclk.max_cdclk_freq)
+		return 0;
+
+	return min_cdclk;
+}
 
 static bool intel_fbc_can_flip_nuke(struct intel_atomic_state *state,
 				    struct intel_crtc *crtc,
diff --git a/drivers/gpu/drm/i915/display/intel_fbc.h b/drivers/gpu/drm/i915/display/intel_fbc.h
index 0e715cb6b4e6..c86562404a00 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.h
+++ b/drivers/gpu/drm/i915/display/intel_fbc.h
@@ -28,6 +28,7 @@ enum intel_fbc_id {
 };
 
 int intel_fbc_atomic_check(struct intel_atomic_state *state);
+int intel_fbc_min_cdclk(const struct intel_crtc_state *crtc_state);
 bool intel_fbc_pre_update(struct intel_atomic_state *state,
 			  struct intel_crtc *crtc);
 void intel_fbc_post_update(struct intel_atomic_state *state,