[PATCH v5 5/7] libweston: fbdev: Attempt to detect the first framebuffer device in the seat. instead of defaulting to /dev/fb0

[Pekka Paalanen]

On Fri, 29 Dec 2017 13:31:51 -0500
nerdopolis <bluescreen_avenger at verizon.net> wrote:

> This adds a function to detect the first framebuffer device in the
> current seat. Instead of hardcoding /dev/fb0, use udev to find the
> first framebuffer device in the seat.
> ---
>  libweston/compositor-fbdev.c | 45 +++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 42 insertions(+), 3 deletions(-)
> 
> diff --git a/libweston/compositor-fbdev.c b/libweston/compositor-fbdev.c
> index 39668aa8..34e6c2f3 100644
> --- a/libweston/compositor-fbdev.c
> +++ b/libweston/compositor-fbdev.c
> @@ -711,6 +711,42 @@ fbdev_restore(struct weston_compositor *compositor)
>  	weston_launcher_restore(compositor->launcher);
>  }
>  
> +static char *
> +find_framebuffer_device(struct fbdev_backend *b, const char *seat)
> +{
> +	struct udev_enumerate *e;
> +	struct udev_list_entry *entry;
> +	const char *path, *device_seat;
> +	char *fb_device;
> +	struct udev_device *device;
> +
> +	e = udev_enumerate_new(b->udev);
> +	udev_enumerate_add_match_subsystem(e, "graphics");
> +	udev_enumerate_add_match_sysname(e, "fb[0-9]*");
> +
> +	udev_enumerate_scan_devices(e);
> +	fb_device = NULL;
> +	udev_list_entry_foreach(entry, udev_enumerate_get_list_entry(e)) {
> +
> +		path = udev_list_entry_get_name(entry);
> +		device = udev_device_new_from_syspath(b->udev, path);
> +		if (!device)
> +			continue;
> +		device_seat = udev_device_get_property_value(device, "ID_SEAT");
> +		if (!device_seat)
> +			device_seat = default_seat;
> +		if (!strcmp(device_seat, seat)) {
> +			fb_device = udev_device_get_devnode(device);
> +			udev_enumerate_unref(e);

Hi,

seems like this should be udev_device_unref() instead, otherwise
'e' is unreffed twice and 'device' is leaked.

> +			break;
> +		}
> +		udev_device_unref(device);
> +	}
> +
> +	udev_enumerate_unref(e);
> +	return fb_device;
> +}
> +
>  static struct fbdev_backend *
>  fbdev_backend_create(struct weston_compositor *compositor,
>                       struct weston_fbdev_backend_config *param)
> @@ -743,6 +779,11 @@ fbdev_backend_create(struct weston_compositor *compositor,
>  		goto out_compositor;
>  	}
>  
> +	if (!param->device)
> +		param->device=find_framebuffer_device(backend, seat_id);
> +	if (!param->device)
> +		param->device=strdup("/dev/fb0");

Missing spaces around '=' on both lines.

The assigned string is leaked, there is no free() for it. However, one
must take care to not free() the string that came as an argument via
weston_fbdev_backend_config struct.

> +
>  	/* Set up the TTY. */
>  	backend->session_listener.notify = session_notify;
>  	wl_signal_add(&compositor->session_signal,
> @@ -790,10 +831,8 @@ out_compositor:
>  static void
>  config_init_to_defaults(struct weston_fbdev_backend_config *config)
>  {
> -	/* TODO: Ideally, available frame buffers should be enumerated using
> -	 * udev, rather than passing a device node in as a parameter. */
>  	config->tty = 0; /* default to current tty */
> -	config->device = "/dev/fb0"; /* default frame buffer */
> +	config->device = NULL;
>  	config->seat_id = NULL;
>  }
>  

Otherwise looks good to me.


Thanks,
pq

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