pm_rps: Use unbuffered I/O on sysfs files

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@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/tests/pm_rps.c b/tests/pm_rps.c
index e8affdb..9123451 100644 (file)
--- a/tests/pm_rps.c
+++ b/tests/pm_rps.c
@@ -22,6 +22,7 @@
  *
  * Authors:
  *    Ben Widawsky <ben@bwidawsk.net>
+ *    Jeff McGee <jeff.mcgee@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);