screencast: add option to force implicit modifier to be linear

Linear buffer layouts are supported by most gpu vendors and as such
should be compatible in mixed mutli gpu setup where the implicit
modifier of one gpu is not supported by the other.

This option should make xdpw work in these environemnts.

The option is marked as experimental since it might be removed if
explicit modifiers provide a better solution.

include/config.h

@@ -11,6 +11,7 @@ struct config_screencast {
 	char *exec_after;
 	char *chooser_cmd;
 	enum xdpw_chooser_types chooser_type;
+	bool force_mod_linear;
 };
 
 struct xdpw_config {

src/core/config.c

@@ -16,6 +16,7 @@ void print_config(enum LOGLEVEL loglevel, struct xdpw_config *config) {
 	logprint(loglevel, "config: exec_after:  %s", config->screencast_conf.exec_after);
 	logprint(loglevel, "config: chooser_cmd: %s", config->screencast_conf.chooser_cmd);
 	logprint(loglevel, "config: chooser_type: %s", chooser_type_str(config->screencast_conf.chooser_type));
+	logprint(loglevel, "config: force_mod_linear: %d", config->screencast_conf.force_mod_linear);
 }
 
 // NOTE: calling finish_config won't prepare the config to be read again from config file
@@ -47,6 +48,18 @@ static void parse_double(double *dest, const char* value) {
 	*dest = strtod(value, (char**)NULL);
 }
 
+static void parse_bool(bool *dest, const char* value) {
+	if (value == NULL || *value == '\0') {
+		logprint(TRACE, "config: skipping empty value in config file");
+		return;
+	}
+	if (strcmp(value, "1") == 0) {
+		*dest = true;
+	} else {
+		*dest = false;
+	}
+}
+
 static int handle_ini_screencast(struct config_screencast *screencast_conf, const char *key, const char *value) {
 	if (strcmp(key, "output_name") == 0) {
 		parse_string(&screencast_conf->output_name, value);
@@ -63,6 +76,8 @@ static int handle_ini_screencast(struct config_screencast *screencast_conf, cons
 		parse_string(&chooser_type, value);
 		screencast_conf->chooser_type = get_chooser_type(chooser_type);
 		free(chooser_type);
+	} else if (strcmp(key, "force_mod_linear") == 0) {
+		parse_bool(&screencast_conf->force_mod_linear, value);
 	} else {
 		logprint(TRACE, "config: skipping invalid key in config file");
 		return 0;

src/screencast/screencast_common.c

@@ -1,3 +1,4 @@
+#include "xdpw.h"
 #include "screencast_common.h"
 #include <assert.h>
 #include <fcntl.h>
@@ -135,10 +136,14 @@ struct xdpw_buffer *xdpw_buffer_create(struct xdpw_screencast_instance *cast,
 			return NULL;
 		}
 		break;
-	case DMABUF:
-		buffer->bo = gbm_bo_create(cast->ctx->gbm,
-				frame_info->width, frame_info->height, frame_info->format,
-				GBM_BO_USE_RENDERING);
+	case DMABUF:;
+		uint32_t flags = GBM_BO_USE_RENDERING;
+		if (cast->ctx->state->config->screencast_conf.force_mod_linear) {
+			flags |= GBM_BO_USE_LINEAR;
+		}
+
+		buffer->bo = gbm_bo_create(cast->ctx->gbm, frame_info->width, frame_info->height,
+				frame_info->format, flags);
 		if (buffer->bo == NULL) {
 			logprint(ERROR, "xdpw: failed to create gbm_bo");
 			free(buffer);

xdg-desktop-portal-wlr.5.scd

@@ -71,6 +71,15 @@ These options need to be placed under the **[screencast]** section.
 	- simple, dmenu: xdpw will launch the chooser given by **chooser_cmd**. For more details
 	  see **OUTPUT CHOOSER**.
 
+**force_mod_linear** = _bool_
+	Force buffers with implicit modifiers to be linear (experimental)
+
+	Setting this option to 1 will force xdpw to allocate dma-bufs with implicit modifier as linear.
+	This option shouldn't be required on single gpu setups, but can increase compatibility
+	especially on setups with multiple gpus.
+
+	This option is experimental and can be removed or replaced in future versions.
+
 ## OUTPUT CHOOSER
 
 The chooser can be any program or script with the following behaviour: