drm/i915/dsc: have intel_dsc_pps_read() return the value

Register read functions usually return the value instead of passing via
pointer parameters. Return the multiple register verification results
via a pointer parameter, which can also be NULL to skip the extra
checks.

Make the name conform to existing style better while at it.

Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/4d08c0f63c4975cc8cd01b0f82845c989bf13dd0.1693933849.git.jani.nikula@intel.com

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

@@ -809,13 +809,14 @@ void intel_dsc_disable(const struct intel_crtc_state *old_crtc_state)
 	}
 }
 
-static bool intel_dsc_read_pps_reg(struct intel_crtc_state *crtc_state,
-				   int pps, u32 *pps_val)
+static u32 intel_dsc_pps_read(struct intel_crtc_state *crtc_state, int pps,
+			      bool *check_equal)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
 	i915_reg_t dsc_reg[2];
 	int i, vdsc_per_pipe, dsc_reg_num;
+	u32 val = 0;
 
 	vdsc_per_pipe = intel_dsc_get_vdsc_per_pipe(crtc_state);
 	dsc_reg_num = min_t(int, ARRAY_SIZE(dsc_reg), vdsc_per_pipe);
@@ -824,20 +825,25 @@ static bool intel_dsc_read_pps_reg(struct intel_crtc_state *crtc_state,
 
 	intel_dsc_get_pps_reg(crtc_state, pps, dsc_reg, dsc_reg_num);
 
-	*pps_val = 0;
+	if (check_equal)
+		*check_equal = true;
 
 	for (i = 0; i < dsc_reg_num; i++) {
-		u32 pps_temp;
+		u32 tmp;
 
-		pps_temp = intel_de_read(i915, dsc_reg[i]);
+		tmp = intel_de_read(i915, dsc_reg[i]);
 
-		if (i == 0)
-			*pps_val = pps_temp;
-		else if (pps_temp != *pps_val)
-			return false;
+		if (i == 0) {
+			val = tmp;
+		} else if (check_equal && tmp != val) {
+			*check_equal = false;
+			break;
+		} else if (!check_equal) {
+			break;
+		}
 	}
 
-	return true;
+	return val;
 }
 
 static u32 intel_dsc_pps_read_and_verify(struct intel_crtc_state *crtc_state, int pps)
@@ -845,10 +851,10 @@ static u32 intel_dsc_pps_read_and_verify(struct intel_crtc_state *crtc_state, in
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
 	u32 val;
-	int ret;
+	bool all_equal;
 
-	ret = intel_dsc_read_pps_reg(crtc_state, pps, &val);
-	drm_WARN_ON(&i915->drm, !ret);
+	val = intel_dsc_pps_read(crtc_state, pps, &all_equal);
+	drm_WARN_ON(&i915->drm, !all_equal);
 
 	return val;
 }