4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Len Brown <len.brown@xxxxxxxxx>
[ Upstream commit 22048c5485503749754b3b5daf9d99ef89fcacdc ]
turbostat displays a GFXMHz column, which comes from reading
/sys/class/graphics/fb0/device/drm/card0/gt_cur_freq_mhz
But GFXMHz was not changing, even when a manual
cat /sys/class/graphics/fb0/device/drm/card0/gt_cur_freq_mhz
showed a new value.
It turns out that a rewind() on the open file is not sufficient,
fflush() (or a close/open) is needed to read fresh values.
Reported-by: Yaroslav Isakov <yaroslav.isakov@xxxxxxxxx>
Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/power/x86/turbostat/turbostat.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -2003,8 +2003,10 @@ int snapshot_gfx_mhz(void)
if (fp == NULL)
fp = fopen_or_die("/sys/class/graphics/fb0/device/drm/card0/gt_cur_freq_mhz", "r");
- else
+ else {
rewind(fp);
+ fflush(fp);
+ }
retval = fscanf(fp, "%d", &gfx_cur_mhz);
if (retval != 1)