[igt-dev] [PATCH i-g-t 5/6] lib/igt_sysfs: Simplify obtaining sysfs path

[Michał Winiarski]

Now that we've extracted card index, we no longer have the need to
iterate over device nodes.

Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
---
 lib/igt_sysfs.c | 29 +++++++----------------------
 1 file changed, 7 insertions(+), 22 deletions(-)

diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
index 13a2ee04..974bf45a 100644
--- a/lib/igt_sysfs.c
+++ b/lib/igt_sysfs.c
@@ -100,6 +100,7 @@ static int writeN(int fd, const char *buf, int len)
 char *igt_sysfs_path(int device, char *path, int pathlen)
 {
 	struct stat st;
+	int ret;
 
 	if (device < 0)
 		return NULL;
@@ -107,30 +108,14 @@ char *igt_sysfs_path(int device, char *path, int pathlen)
 	if (fstat(device, &st) || !S_ISCHR(st.st_mode))
 		return NULL;
 
-	for (int n = 0; n < 16; n++) {
-		int len, ret, maj, min;
-		FILE *file;
-
-		len = snprintf(path, pathlen, "/sys/class/drm/card%d", n);
-
-		sprintf(path + len, "/dev");
-		file = fopen(path, "r");
-		if (!file)
-			continue;
-
-		ret = fscanf(file, "%d:%d", &maj, &min);
-		fclose(file);
+	snprintf(path, pathlen, "/sys/dev/char/%d:%d",
+		 major(st.st_rdev), minor(st.st_rdev));
 
-		if (ret != 2 || major(st.st_rdev) != maj ||
-		    minor(st.st_rdev) != min)
-			continue;
-
-		path[len] = '\0';
-
-		return path;
-	}
+	ret = access(path, F_OK);
+	if (ret)
+		return NULL;
 
-	return NULL;
+	return path;
 }
 
 /**
-- 
2.20.1