Re: [PATCH v7 5/6] compositor-fbdev: detect the first fb device in the seat
On 27 June 2018 at 00:39, nerdopolis wrote:
> This adds a function to detect the first framebuffer device in the
> current seat. Instead of hardcoding /dev/fb0, detect the device
> with udev, favoring the boot_vga device, and falling back to the
> first framebuffer device in the seat if there is none. This is very
> similar to what compositor-drm does to find display devices
> ---
> libweston/compositor-fbdev.c | 83 ++--
> 1 file changed, 80 insertions(+), 3 deletions(-)
>
> diff --git a/libweston/compositor-fbdev.c b/libweston/compositor-fbdev.c
> index e3777495..616300dc 100644
> --- a/libweston/compositor-fbdev.c
> +++ b/libweston/compositor-fbdev.c
> @@ -777,6 +777,77 @@ session_notify(struct wl_listener *listener, void *data)
> }
> }
>
> +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, *id, *fb_device_path;
> + struct udev_device *device, *fb_device, *pci;
> +
> + 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)) {
> + bool is_boot_vga = false;
> +
> + 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)) {
> + udev_device_unref(device);
> + continue;
> + }
> +
> + pci = udev_device_get_parent_with_subsystem_devtype(device,
> + "pci", NULL);
> + if (pci) {
> + id = udev_device_get_sysattr_value(pci, "boot_vga");
> + if (id && !strcmp(id, "1"))
> + is_boot_vga = true;
> + }
> +
> + /* If a framebuffer device was found, and this device isn't
> +* the boot-VGA device, don't use it. */
> + if (!is_boot_vga && fb_device) {
> + udev_device_unref(device);
> + continue;
> + }
> +
> + /* There can only be one boot_vga device. Try to use it
> +* at all costs. */
> + if (is_boot_vga) {
> + if (fb_device)
> + udev_device_unref(fb_device);
> + fb_device = device;
> + break;
> + }
> +
> + /* Per the (!is_boot_vga && fb_device) test above, only
> +* trump existing saved devices with boot-VGA devices, so if
> +* the test ends up here, this must be the first device seen.
> */
> + assert(!fb_device);
> + fb_device = device;
> + }
> +
> + udev_enumerate_unref(e);
> +
This function (barring the if bellow) seems mostly identical to the
one in compositor-drm.c
Might be a good idea to make it a helper vaguely alike
struct udev_device *
foo(struct backend *b, const char *seat, const char *subsys, const
char *sysname,
int (*predicate)(struct backend b*, struct udev_device *d))
The callers will be as trivial as
foo(b, seat, "drm", "card[0-9]*", drm_device_is_kms);
foo(b, seat, "graphics", "fb[0-9]*", NULL);
You'd want to do this at some point, since close to nobody tests
fbdev. I think that people porting any drm fixes to fbdev is even less
;-)
> + if (fb_device)
> + {
> + fb_device_path=strdup(udev_device_get_devnode(fb_device));
> + udev_device_unref(fb_device);
> + }
> +
Obviously this trivial hunk will have to stay in fbdev.
HTH
Emil
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[PATCH v7 5/6] compositor-fbdev: detect the first fb device in the seat
This adds a function to detect the first framebuffer device in the
current seat. Instead of hardcoding /dev/fb0, detect the device
with udev, favoring the boot_vga device, and falling back to the
first framebuffer device in the seat if there is none. This is very
similar to what compositor-drm does to find display devices
---
libweston/compositor-fbdev.c | 83 ++--
1 file changed, 80 insertions(+), 3 deletions(-)
diff --git a/libweston/compositor-fbdev.c b/libweston/compositor-fbdev.c
index e3777495..616300dc 100644
--- a/libweston/compositor-fbdev.c
+++ b/libweston/compositor-fbdev.c
@@ -777,6 +777,77 @@ session_notify(struct wl_listener *listener, void *data)
}
}
+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, *id, *fb_device_path;
+ struct udev_device *device, *fb_device, *pci;
+
+ 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)) {
+ bool is_boot_vga = false;
+
+ 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)) {
+ udev_device_unref(device);
+ continue;
+ }
+
+ pci = udev_device_get_parent_with_subsystem_devtype(device,
+ "pci", NULL);
+ if (pci) {
+ id = udev_device_get_sysattr_value(pci, "boot_vga");
+ if (id && !strcmp(id, "1"))
+ is_boot_vga = true;
+ }
+
+ /* If a framebuffer device was found, and this device isn't
+* the boot-VGA device, don't use it. */
+ if (!is_boot_vga && fb_device) {
+ udev_device_unref(device);
+ continue;
+ }
+
+ /* There can only be one boot_vga device. Try to use it
+* at all costs. */
+ if (is_boot_vga) {
+ if (fb_device)
+ udev_device_unref(fb_device);
+ fb_device = device;
+ break;
+ }
+
+ /* Per the (!is_boot_vga && fb_device) test above, only
+* trump existing saved devices with boot-VGA devices, so if
+* the test ends up here, this must be the first device seen. */
+ assert(!fb_device);
+ fb_device = device;
+ }
+
+ udev_enumerate_unref(e);
+
+ if (fb_device)
+ {
+ fb_device_path=strdup(udev_device_get_devnode(fb_device));
+ udev_device_unref(fb_device);
+ }
+
+ return fb_device_path;
+}
+
static struct fbdev_backend *
fbdev_backend_create(struct weston_compositor *compositor,
struct weston_fbdev_backend_config *param)
@@ -809,6 +880,11 @@ 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");
+
/* Set up the TTY. */
backend->session_listener.notify = session_notify;
wl_signal_add(>session_signal,
@@ -835,12 +911,15 @@ fbdev_backend_create(struct weston_compositor *compositor,
if (!fbdev_head_create(backend, param->device))
goto out_launcher;
+ free(param->device);
+
udev_input_init(>input, compositor, backend->udev,
seat_id, param->configure_device);
return backend;
out_launcher:
+ free(param->device);
weston_launcher_destroy(compositor->launcher);
out_udev:
@@ -856,10 +935,8 @@ 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;
}
--
2.17.1
___
