drm: Code stereo layouts as an enum rather than a bit field

This allows us to use fewer bits in the mode structure, leaving room for
future work while allowing more stereo layouts types than we could have
ever dreamt of.

I also exposed the previously private DRM_MODE_FLAG_3D_MASK to set in
stone that we are using 5 bits for the stereo layout enum, reserving 32
values.

Even with that reservation, we gain 3 bits from the previous encoding.

The code adding the mandatory stereo modes needeed to be adapted as it was
relying or being able to or stereo layouts together.
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_edid.c

@@ -2562,16 +2562,16 @@ struct stereo_mandatory_mode {
 };
 
 static const struct stereo_mandatory_mode stereo_mandatory_modes[] = {
-	{ 1920, 1080, 24,
-	  DRM_MODE_FLAG_3D_TOP_AND_BOTTOM | DRM_MODE_FLAG_3D_FRAME_PACKING },
+	{ 1920, 1080, 24, DRM_MODE_FLAG_3D_TOP_AND_BOTTOM },
+	{ 1920, 1080, 24, DRM_MODE_FLAG_3D_FRAME_PACKING },
 	{ 1920, 1080, 50,
 	  DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_3D_SIDE_BY_SIDE_HALF },
 	{ 1920, 1080, 60,
 	  DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_3D_SIDE_BY_SIDE_HALF },
-	{ 1280, 720,  50,
-	  DRM_MODE_FLAG_3D_TOP_AND_BOTTOM | DRM_MODE_FLAG_3D_FRAME_PACKING },
-	{ 1280, 720,  60,
-	  DRM_MODE_FLAG_3D_TOP_AND_BOTTOM | DRM_MODE_FLAG_3D_FRAME_PACKING }
+	{ 1280, 720,  50, DRM_MODE_FLAG_3D_TOP_AND_BOTTOM },
+	{ 1280, 720,  50, DRM_MODE_FLAG_3D_FRAME_PACKING },
+	{ 1280, 720,  60, DRM_MODE_FLAG_3D_TOP_AND_BOTTOM },
+	{ 1280, 720,  60, DRM_MODE_FLAG_3D_FRAME_PACKING }
 };
 
 static bool
@@ -2586,50 +2586,33 @@ stereo_match_mandatory(const struct drm_display_mode *mode,
 	       drm_mode_vrefresh(mode) == stereo_mode->vrefresh;
 }
 
-static const struct stereo_mandatory_mode *
-hdmi_find_stereo_mandatory_mode(const struct drm_display_mode *mode)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(stereo_mandatory_modes); i++)
-		if (stereo_match_mandatory(mode, &stereo_mandatory_modes[i]))
-			return &stereo_mandatory_modes[i];
-
-	return NULL;
-}
-
 static int add_hdmi_mandatory_stereo_modes(struct drm_connector *connector)
 {
 	struct drm_device *dev = connector->dev;
 	const struct drm_display_mode *mode;
 	struct list_head stereo_modes;
-	int modes = 0;
+	int modes = 0, i;
 
 	INIT_LIST_HEAD(&stereo_modes);
 
 	list_for_each_entry(mode, &connector->probed_modes, head) {
+		for (i = 0; i < ARRAY_SIZE(stereo_mandatory_modes); i++) {
 			const struct stereo_mandatory_mode *mandatory;
-		u32 stereo_layouts, layout;
-
-		mandatory = hdmi_find_stereo_mandatory_mode(mode);
-		if (!mandatory)
-			continue;
-
-		stereo_layouts = mandatory->flags & DRM_MODE_FLAG_3D_MASK;
-		do {
 			struct drm_display_mode *new_mode;
 
-			layout = 1 << (ffs(stereo_layouts) - 1);
-			stereo_layouts &= ~layout;
+			if (!stereo_match_mandatory(mode,
+						    &stereo_mandatory_modes[i]))
+				continue;
 
+			mandatory = &stereo_mandatory_modes[i];
 			new_mode = drm_mode_duplicate(dev, mode);
 			if (!new_mode)
 				continue;
 
-			new_mode->flags |= layout;
+			new_mode->flags |= mandatory->flags;
 			list_add_tail(&new_mode->head, &stereo_modes);
 			modes++;
-		} while (stereo_layouts);
+		}
 	}
 
 	list_splice_tail(&stereo_modes, &connector->probed_modes);

include/drm/drm_crtc.h

@@ -181,15 +181,6 @@ struct drm_display_mode {
 	int hsync;		/* in kHz */
 };
 
-#define DRM_MODE_FLAG_3D_MASK	(DRM_MODE_FLAG_3D_FRAME_PACKING		| \
-				 DRM_MODE_FLAG_3D_FIELD_ALTERNATIVE	| \
-				 DRM_MODE_FLAG_3D_LINE_ALTERNATIVE	| \
-				 DRM_MODE_FLAG_3D_SIDE_BY_SIDE_FULL	| \
-				 DRM_MODE_FLAG_3D_L_DEPTH		| \
-				 DRM_MODE_FLAG_3D_L_DEPTH_GFX_GFX_DEPTH | \
-				 DRM_MODE_FLAG_3D_TOP_AND_BOTTOM	| \
-				 DRM_MODE_FLAG_3D_SIDE_BY_SIDE_HALF)
-
 static inline bool drm_mode_is_stereo(const struct drm_display_mode *mode)
 {
 	return mode->flags & DRM_MODE_FLAG_3D_MASK;

include/uapi/drm/drm_mode.h

@@ -58,14 +58,17 @@
 #define DRM_MODE_FLAG_PIXMUX			(1<<11)
 #define DRM_MODE_FLAG_DBLCLK			(1<<12)
 #define DRM_MODE_FLAG_CLKDIV2			(1<<13)
+#define DRM_MODE_FLAG_3D_MASK			(0x1f<<14)
+#define  DRM_MODE_FLAG_3D_NONE			(0<<14)
 #define  DRM_MODE_FLAG_3D_FRAME_PACKING		(1<<14)
-#define DRM_MODE_FLAG_3D_FIELD_ALTERNATIVE	(1<<15)
-#define DRM_MODE_FLAG_3D_LINE_ALTERNATIVE	(1<<16)
-#define DRM_MODE_FLAG_3D_SIDE_BY_SIDE_FULL	(1<<17)
-#define DRM_MODE_FLAG_3D_L_DEPTH		(1<<18)
-#define DRM_MODE_FLAG_3D_L_DEPTH_GFX_GFX_DEPTH	(1<<19)
-#define DRM_MODE_FLAG_3D_TOP_AND_BOTTOM		(1<<20)
-#define DRM_MODE_FLAG_3D_SIDE_BY_SIDE_HALF	(1<<21)
+#define  DRM_MODE_FLAG_3D_FIELD_ALTERNATIVE	(2<<14)
+#define  DRM_MODE_FLAG_3D_LINE_ALTERNATIVE	(3<<14)
+#define  DRM_MODE_FLAG_3D_SIDE_BY_SIDE_FULL	(4<<14)
+#define  DRM_MODE_FLAG_3D_L_DEPTH		(5<<14)
+#define  DRM_MODE_FLAG_3D_L_DEPTH_GFX_GFX_DEPTH	(6<<14)
+#define  DRM_MODE_FLAG_3D_TOP_AND_BOTTOM	(7<<14)
+#define  DRM_MODE_FLAG_3D_SIDE_BY_SIDE_HALF	(8<<14)
+
 
 /* DPMS flags */
 /* bit compatible with the xorg definitions. */