Use sysfs to locate devices nodes
authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Fri, 20 Aug 2010 08:57:19 +0000 (10:57 +0200)
committerLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Fri, 20 Aug 2010 08:57:19 +0000 (10:57 +0200)
Changes made during the v4l2_subdev API review renamed the /dev/subdev*
device nodes to /dev/v4l-subdev*. Instead of hardcoding the names in the
media-ctl application, use sysfs to retrieve the kernel device name and
assume the device node name is identical.

This isn't a perfect solution, we should really use libudev, but it will
do for now.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
media.c

diff --git a/media.c b/media.c
index aaa1005..1bc39e1 100644 (file)
--- a/media.c
+++ b/media.c
@@ -430,9 +430,11 @@ static int media_enum_entities(struct media_device *media)
 {
        struct media_entity *entity;
        struct stat devstat;
 {
        struct media_entity *entity;
        struct stat devstat;
-       char devname[32];
        unsigned int size;
        unsigned int size;
-       unsigned int i;
+       char devname[32];
+       char sysname[32];
+       char target[1024];
+       char *p;
        __u32 id;
        int ret;
 
        __u32 id;
        int ret;
 
@@ -465,24 +467,29 @@ static int media_enum_entities(struct media_device *media)
                    (entity->info.type != MEDIA_ENTITY_TYPE_SUBDEV))
                        continue;
 
                    (entity->info.type != MEDIA_ENTITY_TYPE_SUBDEV))
                        continue;
 
-               for (i = 0; i < 256; ++i) {
-                       if (entity->info.type == MEDIA_ENTITY_TYPE_NODE)
-                               sprintf(devname, "/dev/video%u", i);
-                       else
-                               sprintf(devname, "/dev/subdev%u", i);
+               sprintf(sysname, "/sys/dev/char/%u:%u", entity->info.v4l.major,
+                       entity->info.v4l.minor);
+               ret = readlink(sysname, target, sizeof(target));
+               if (ret < 0)
+                       continue;
 
 
-                       ret = stat(devname, &devstat);
-                       if (ret < 0)
-                               continue;
+               target[ret] = '\0';
+               p = strrchr(target, '/');
+               if (p == NULL)
+                       continue;
 
 
-                       if (major(devstat.st_rdev) == entity->info.v4l.major &&
-                           minor(devstat.st_rdev) == entity->info.v4l.minor) {
-                               strcpy(entity->devname, devname);
-                               break;
-                       }
-               }
+               sprintf(devname, "/dev/%s", p + 1);
+               ret = stat(devname, &devstat);
+               if (ret < 0)
+                       continue;
 
 
-               id = entity->info.id;
+               /* Sanity check: udev might have reordered the device nodes.
+                * Make sure the major/minor match. We should really use
+                * libudev.
+                */
+               if (major(devstat.st_rdev) == entity->info.v4l.major &&
+                   minor(devstat.st_rdev) == entity->info.v4l.minor)
+                       strcpy(entity->devname, devname);
        }
 
        return 0;
        }
 
        return 0;