drm/i915/adlp: Add PIPE_MISC2 programming

When scalers are enabled, we need to program underrun
bubble counter to 0x50 to avoid Soft Pipe A underruns.
Make sure other bits dont get overwritten.

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Clint Taylor <clinton.a.taylor@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Clinton Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Clint Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210519000625.3184321-17-lucas.demarchi@intel.com

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

@@ -5716,8 +5716,12 @@ static void hsw_set_pipeconf(const struct intel_crtc_state *crtc_state)
 static void bdw_set_pipemisc(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+	const struct intel_crtc_scaler_state *scaler_state =
+		&crtc_state->scaler_state;
+
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	u32 val = 0;
+	int i;
 
 	switch (crtc_state->pipe_bpp) {
 	case 18:
@@ -5756,6 +5760,23 @@ static void bdw_set_pipemisc(const struct intel_crtc_state *crtc_state)
 	if (DISPLAY_VER(dev_priv) >= 12)
 		val |= PIPEMISC_PIXEL_ROUNDING_TRUNC;
 
+	if (IS_ALDERLAKE_P(dev_priv)) {
+		bool scaler_in_use = false;
+
+		for (i = 0; i < crtc->num_scalers; i++) {
+			if (!scaler_state->scalers[i].in_use)
+				continue;
+
+			scaler_in_use = true;
+			break;
+		}
+
+		intel_de_rmw(dev_priv, PIPE_MISC2(crtc->pipe),
+			     PIPE_MISC2_UNDERRUN_BUBBLE_COUNTER_MASK,
+			     scaler_in_use ? PIPE_MISC2_BUBBLE_COUNTER_SCALER_EN :
+			     PIPE_MISC2_BUBBLE_COUNTER_SCALER_DIS);
+	}
+
 	intel_de_write(dev_priv, PIPEMISC(crtc->pipe), val);
 }
 

drivers/gpu/drm/i915/i915_reg.h

@@ -6155,6 +6155,13 @@ enum {
 #define   PIPEMISC_DITHER_TYPE_SP	(0 << 2)
 #define PIPEMISC(pipe)			_MMIO_PIPE2(pipe, _PIPE_MISC_A)
 
+#define _PIPE_MISC2_A					0x7002C
+#define _PIPE_MISC2_B					0x7102C
+#define   PIPE_MISC2_BUBBLE_COUNTER_SCALER_EN		(0x50 << 24)
+#define   PIPE_MISC2_BUBBLE_COUNTER_SCALER_DIS		(0x14 << 24)
+#define   PIPE_MISC2_UNDERRUN_BUBBLE_COUNTER_MASK	(0xff << 24)
+#define PIPE_MISC2(pipe)					_MMIO_PIPE2(pipe, _PIPE_MISC2_A)
+
 /* Skylake+ pipe bottom (background) color */
 #define _SKL_BOTTOM_COLOR_A		0x70034
 #define   SKL_BOTTOM_COLOR_GAMMA_ENABLE	(1 << 31)