drm: Find a proper modeset device, is none is provided

Instead of having a fixed /dev/dri/card0 default, iterate
over primary devices until one with modeset capabilities
is found.

This is quite useful when a render-only driver
(such as lima or panfrost) was registered before the modeset
driver, taking over /dev/dri/card0.

While here, add a warning for devices explicitly set via -D,
by checking if they look like a modeset device.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/kmscube.c b/kmscube.c
index 81803be..90de638 100644
--- a/kmscube.c
+++ b/kmscube.c
@@ -76,7 +76,7 @@ static void usage(const char *name)
 
 int main(int argc, char *argv[])
 {
-	const char *device = "/dev/dri/card0";
+	const char *device = NULL;
 	const char *video = NULL;
 	char mode_str[DRM_DISPLAY_MODE_LEN] = "";
 	char *p;