[Intel-gfx] [PATCH i-g-t v2] lib/pm: Wait a little for sound module load to complete

[Chris Wilson]

Sometimes we may probe the sound module as it is still being registered
and its debugfs not yet fully populated. If we do not find a file we
expect to exist, sleep a little and check again.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107801
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Imre Deak <imre.deak at linux.com>
---
 lib/igt_pm.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/lib/igt_pm.c b/lib/igt_pm.c
index 339a51e6f..c18bb87c6 100644
--- a/lib/igt_pm.c
+++ b/lib/igt_pm.c
@@ -154,20 +154,28 @@ static int __igt_pm_enable_audio_runtime_pm(void)
 	while ((de = readdir(dir))) {
 		const char *match = "hwC";
 		char buf[32] = { }; /* for Valgrind */
-		char *tmp;
+		int loops = 500;
+		int base;
 		int ret;
 
 		if (de->d_type != DT_LNK ||
 		    strncmp(de->d_name, match, strlen(match)))
 			continue;
 
-		igt_assert(asprintf(&tmp,
-				    "/sys/class/sound/%s/vendor_name",
-				    de->d_name));
+		base = openat(dirfd(dir), de->d_name, O_RDONLY);
+		igt_assert_fd(base);
+
+		do {
+			fd = open(base, "vendor_name", O_RDONLY);
+			if (fd < 0) /* module is still loading? */
+				usleep(1000);
+			else
+				break;
+		} while (--loops);
+		close(base);
+		if (fd < 0)
+			continue;
 
-		fd = open(tmp, O_RDONLY);
-		free(tmp);
-		igt_assert_fd(fd);
 		ret = read(fd, buf, sizeof(buf));
 		close(fd);
 		igt_assert(ret > 0);
-- 
2.19.0.rc1