1 files changed, 38 insertions, 0 deletions

diff --git a/sway/config/output.c b/sway/config/output.c
index 6d39c2f5..63c81382 100644
--- a/sway/config/output.c
+++ b/sway/config/output.c
@@ -1,5 +1,6 @@
 #define _POSIX_C_SOURCE 200809L
 #include <assert.h>
+#include <drm_fourcc.h>
 #include <stdbool.h>
 #include <string.h>
 #include <sys/socket.h>
@@ -67,6 +68,7 @@ struct output_config *new_output_config(const char *name) {
         oc->subpixel = WL_OUTPUT_SUBPIXEL_UNKNOWN;
         oc->max_render_time = -1;
         oc->adaptive_sync = -1;
+        oc->render_bit_depth = RENDER_BIT_DEPTH_DEFAULT;
         return oc;
 }
 
@@ -113,6 +115,9 @@ void merge_output_config(struct output_config *dst, struct output_config *src) {
         if (src->adaptive_sync != -1) {
                 dst->adaptive_sync = src->adaptive_sync;
         }
+        if (src->render_bit_depth != RENDER_BIT_DEPTH_DEFAULT) {
+                dst->render_bit_depth = src->render_bit_depth;
+        }
         if (src->background) {
                 free(dst->background);
                 dst->background = strdup(src->background);
@@ -351,6 +356,23 @@ static int compute_default_scale(struct wlr_output *output) {
         return 2;
 }
 
+/* Lists of formats to try, in order, when a specific render bit depth has
+ * been asked for. The second to last format in each list should always
+ * be XRGB8888, as a reliable backup in case the others are not available;
+ * the last should be DRM_FORMAT_INVALID, to indicate the end of the list. */
+static const uint32_t *bit_depth_preferences[] = {
+        [RENDER_BIT_DEPTH_8] = (const uint32_t []){
+                DRM_FORMAT_XRGB8888,
+                DRM_FORMAT_INVALID,
+        },
+        [RENDER_BIT_DEPTH_10] = (const uint32_t []){
+                DRM_FORMAT_XRGB2101010,
+                DRM_FORMAT_XBGR2101010,
+                DRM_FORMAT_XRGB8888,
+                DRM_FORMAT_INVALID,
+        },
+};
+
 static void queue_output_config(struct output_config *oc,
                 struct sway_output *output) {
         if (output == root->noop_output) {
@@ -437,6 +459,22 @@ static void queue_output_config(struct output_config *oc,
                         oc->adaptive_sync);
                 wlr_output_enable_adaptive_sync(wlr_output, oc->adaptive_sync == 1);
         }
+
+        if (oc && oc->render_bit_depth != RENDER_BIT_DEPTH_DEFAULT) {
+                const uint32_t *fmts = bit_depth_preferences[oc->render_bit_depth];
+                assert(fmts);
+
+                for (size_t i = 0; fmts[i] != DRM_FORMAT_INVALID; i++) {
+                        wlr_output_set_render_format(wlr_output, fmts[i]);
+                        if (wlr_output_test(wlr_output)) {
+                                break;
+                        }
+
+                        sway_log(SWAY_DEBUG, "Preferred output format 0x%08x "
+                                "failed to work, falling back to next in "
+                                "list, 0x%08x", fmts[i], fmts[i + 1]);
+                }
+        }
 }
 
 bool apply_output_config(struct output_config *oc, struct sway_output *output) {