glamor: Add glamor_shareable_fd_from_pixmap()

Add glamor_shareable_fd_from_pixmap function to get dma-buf fds suitable
for sharing across GPUs (not using GPU specific tiling).

This is necessary for the modesetting driver to correctly implement
the DRI2 SharePixmapBacking callback.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Keith Packard <keithp@keithp.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/glamor/glamor.c b/glamor/glamor.c
index 5ba440c83..903f6bdf6 100644
--- a/glamor/glamor.c
+++ b/glamor/glamor.c
@@ -821,6 +821,26 @@ glamor_fd_from_pixmap(ScreenPtr screen,
     return -1;
 }
 
+_X_EXPORT int
+glamor_shareable_fd_from_pixmap(ScreenPtr screen,
+                                PixmapPtr pixmap, CARD16 *stride, CARD32 *size)
+{
+    unsigned orig_usage_hint = pixmap->usage_hint;
+    int ret;
+
+    /*
+     * The actual difference between a sharable and non sharable buffer
+     * is decided 4 call levels deep in glamor_make_pixmap_exportable()
+     * based on pixmap->usage_hint == CREATE_PIXMAP_USAGE_SHARED
+     * 2 of those calls are also exported API, so we cannot just add a flag.
+     */
+    pixmap->usage_hint = CREATE_PIXMAP_USAGE_SHARED;
+    ret = glamor_fd_from_pixmap(screen, pixmap, stride, size);
+    pixmap->usage_hint = orig_usage_hint;
+
+    return ret;
+}
+
 int
 glamor_name_from_pixmap(PixmapPtr pixmap, CARD16 *stride, CARD32 *size)
 {