drm/i915/sdvo: Filter out invalid outputs more sensibly

We try to filter out the corresponding xxx1 output
if the xxx0 output is not present. But the way that is
being done is pretty awkward. Make it less so.

Cc: stable@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221026101134.20865-2-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

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

@@ -2934,16 +2934,33 @@ intel_sdvo_lvds_init(struct intel_sdvo *intel_sdvo, int device)
 	return false;
 }
 
+static u16 intel_sdvo_filter_output_flags(u16 flags)
+{
+	flags &= SDVO_OUTPUT_MASK;
+
+	/* SDVO requires XXX1 function may not exist unless it has XXX0 function.*/
+	if (!(flags & SDVO_OUTPUT_TMDS0))
+		flags &= ~SDVO_OUTPUT_TMDS1;
+
+	if (!(flags & SDVO_OUTPUT_RGB0))
+		flags &= ~SDVO_OUTPUT_RGB1;
+
+	if (!(flags & SDVO_OUTPUT_LVDS0))
+		flags &= ~SDVO_OUTPUT_LVDS1;
+
+	return flags;
+}
+
 static bool
 intel_sdvo_output_setup(struct intel_sdvo *intel_sdvo, u16 flags)
 {
-	/* SDVO requires XXX1 function may not exist unless it has XXX0 function.*/
+	flags = intel_sdvo_filter_output_flags(flags);
 
 	if (flags & SDVO_OUTPUT_TMDS0)
 		if (!intel_sdvo_dvi_init(intel_sdvo, 0))
 			return false;
 
-	if ((flags & SDVO_TMDS_MASK) == SDVO_TMDS_MASK)
+	if (flags & SDVO_OUTPUT_TMDS1)
 		if (!intel_sdvo_dvi_init(intel_sdvo, 1))
 			return false;
 
@@ -2964,7 +2981,7 @@ intel_sdvo_output_setup(struct intel_sdvo *intel_sdvo, u16 flags)
 		if (!intel_sdvo_analog_init(intel_sdvo, 0))
 			return false;
 
-	if ((flags & SDVO_RGB_MASK) == SDVO_RGB_MASK)
+	if (flags & SDVO_OUTPUT_RGB1)
 		if (!intel_sdvo_analog_init(intel_sdvo, 1))
 			return false;
 
@@ -2972,11 +2989,11 @@ intel_sdvo_output_setup(struct intel_sdvo *intel_sdvo, u16 flags)
 		if (!intel_sdvo_lvds_init(intel_sdvo, 0))
 			return false;
 
-	if ((flags & SDVO_LVDS_MASK) == SDVO_LVDS_MASK)
+	if (flags & SDVO_OUTPUT_LVDS1)
 		if (!intel_sdvo_lvds_init(intel_sdvo, 1))
 			return false;
 
-	if ((flags & SDVO_OUTPUT_MASK) == 0) {
+	if (flags == 0) {
 		unsigned char bytes[2];
 
 		intel_sdvo->controlled_output = 0;