From: Len Brown <len.brown@intel.com>
Date: Sat, 4 Mar 2017 20:42:48 +0000 (-0500)
Subject: tools/power turbostat: bugfix: GFXMHz column not changing
X-Git-Tag: archive/raspbian/4.9.80-2+rpi1~7^2~1791
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=86c469bea4ae129433d119b7eb178d40421db045;p=linux-4.9.git

tools/power turbostat: bugfix: GFXMHz column not changing


[ 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@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 3e199b508a96..9664b1ff4285 100644
--- 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)