From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
There is no need to iterate over /sys/class/drm/card* directories looking
for the one which matches our major and minor, when we can directly find
the right one via the /sys/dev/char/<major>:<minor> symlink.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Suggested-by: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
---
lib/igt_sysfs.c | 36 ++++++++++++------------------------
1 file changed, 12 insertions(+), 24 deletions(-)
diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
index f0fef8d434ef..a4a87711ed0c 100644
--- a/lib/igt_sysfs.c
+++ b/lib/igt_sysfs.c
@@ -100,40 +100,28 @@ static int writeN(int fd, const char *buf, int len)
*/
char *igt_sysfs_path(int device, char *path, int pathlen, int *idx)
{
+ unsigned int maj, min;
struct stat st;
+ int len;
if (device < 0 || fstat(device, &st) || !S_ISCHR(st.st_mode))
return NULL;
+ maj = major(st.st_rdev);
+ min = minor(st.st_rdev);
+
/* Only support master nodes. */
- if (minor(st.st_rdev) >= 64)
+ if (min >= 64)
return NULL;
- for (int n = 0; n < 16; n++) {
- int len = snprintf(path, pathlen, "/sys/class/drm/card%d", n);
- int ret, maj, min;
- FILE *file;
-
- sprintf(path + len, "/dev");
- file = fopen(path, "r");
- if (!file)
- continue;
-
- ret = fscanf(file, "%d:%d", &maj, &min);
- fclose(file);
-
- if (ret != 2 ||
- major(st.st_rdev) != maj ||
- minor(st.st_rdev) != min)
- continue;
+ len = snprintf(path, pathlen, "/sys/dev/char/%u:%u", maj, min);
+ if (len == pathlen)
+ return NULL;
- path[len] = '\0';
- if (idx)
- *idx = n;
- return path;
- }
+ if (idx)
+ *idx = min;
- return NULL;
+ return path;
}
/**
--
2.14.1
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