[Intel-gfx] [PATCH 1/4] pm_rps: Use unbuffered I/O on sysfs files

[jeff.mcgee at intel.com]

From: Jeff McGee <jeff.mcgee at intel.com>

Bionic C library may not re-read a buffered, read-only file which
results in failure to monitor changes in gt_cur_freq_mhz.

Signed-off-by: Jeff McGee <jeff.mcgee at intel.com>
---
 tests/pm_rps.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/tests/pm_rps.c b/tests/pm_rps.c
index e8affdb..9123451 100644
--- a/tests/pm_rps.c
+++ b/tests/pm_rps.c
@@ -22,6 +22,7 @@
  *
  * Authors:
  *    Ben Widawsky <ben at bwidawsk.net>
+ *    Jeff McGee <jeff.mcgee at intel.com>
  *
  */
 
@@ -66,7 +67,6 @@ static int readval(FILE *filp)
 	int val;
 	int scanned;
 
-	fflush(filp);
 	rewind(filp);
 	scanned = fscanf(filp, "%d", &val);
 	igt_assert(scanned == 1);
@@ -76,15 +76,11 @@ static int readval(FILE *filp)
 
 static int do_writeval(FILE *filp, int val, int lerrno)
 {
-	/* Must write twice to sysfs since the first one simply calculates the size and won't return the error */
 	int ret;
 	rewind(filp);
 	ret = fprintf(filp, "%d", val);
-	rewind(filp);
-	ret = fprintf(filp, "%d", val);
 	if (ret && lerrno)
 		igt_assert(errno = lerrno);
-	fflush(filp);
 	return ret;
 }
 #define writeval(filp, val) do_writeval(filp, val, 0)
@@ -146,6 +142,7 @@ igt_simple_main
 		igt_assert(ret != -1);
 		junk->filp = fopen(path, junk->mode);
 		igt_require(junk->filp);
+		setbuf(junk->filp, NULL);
 
 		val = readval(junk->filp);
 		igt_assert(val >= 0);
-- 
1.8.5.2