Make sure cpupower starts after the list of governors is available

On EeePC 1015 PED (in Live mode), cpupower.service seemed to start too
early, before /sys/devices/.../scaling_available_governors was there,
and failed as a result. There were no such problems on faster machines,
but still.

Now cpupower.service will start only when 'scaling_available_governors'
file is available. cpupower.path unit handles this. If CPU frequency
scaling is not supported the file will never appear and cpupower.service
will not start at all, which is natural.

cpupower.path

@@ -0,0 +1,9 @@
+[Unit]
+Description=cpupower - wait for the list of frequency governors
+After=syslog.target
+
+[Path]
+PathExists=/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
+
+[Install]
+WantedBy=multi-user.target

cpupower.service

@@ -1,6 +1,7 @@
 [Unit]
 Description=Configure CPU frequency settings
 After=syslog.target
+ConditionPathExists=/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
 
 [Service]
 Type=oneshot
@@ -10,3 +11,4 @@ ExecStart=/usr/bin/cpupower-start.sh
 
 [Install]
 WantedBy=multi-user.target
+Also=cpupower.path

kernel.spec

@@ -29,7 +29,7 @@
 %define rpmrel		%mkrel 0.%{kpatch}.%{mibrel}
 %endif
 %else
-%define rpmrel		3
+%define rpmrel		4
 %endif
 
 # fakerel and fakever never change, they are used to fool
@@ -349,10 +349,11 @@ Source2: 	disable-mrproper-prepare-scripts-configs-in-devel-rpms.patch
 Source4: 	README.kernel-sources
 Source5:	kernel.rpmlintrc
 
-# Cpupower: the service, the config and the wrapper script
+# Cpupower: the service, the config, etc.
 Source50:	cpupower.service
 Source51:	cpupower.config
 Source52:	cpupower-start.sh
+Source53:	cpupower.path
 
 # Our patch tarball, 
 # see https://abf.rosalinux.ru/soft/kernel-patches-and-configs/
@@ -1038,14 +1039,16 @@ The cpupower tools.
 %post -n cpupower
 
 if [ $1 -ge 0 ]; then
-	/bin/systemctl enable cpupower >/dev/null 2>&1 || :
-	/bin/systemctl start cpupower >/dev/null 2>&1 || :
+# Do not enable/disable cpupower.service directly, because it should start
+# when cpupower.path triggers it.
+	/bin/systemctl enable cpupower.path >/dev/null 2>&1 || :
+	/bin/systemctl start cpupower.path >/dev/null 2>&1 || :
 fi
 
 %preun -n cpupower
 if [ $1 -eq 0 ]; then
-        /bin/systemctl --no-reload disable cpupower > /dev/null 2>&1 || :
-        /bin/systemctl stop cpupower > /dev/null 2>&1 || :
+        /bin/systemctl --no-reload disable cpupower.path > /dev/null 2>&1 || :
+        /bin/systemctl stop cpupower.path > /dev/null 2>&1 || :
 fi
 
 %package -n cpupower-devel
@@ -1836,6 +1839,7 @@ mv cpupower.lang ../
 chmod 0755 %{buildroot}%{_libdir}/libcpupower.so*
 mkdir -p %{buildroot}%{_unitdir} %{buildroot}%{_sysconfdir}/sysconfig
 install -m644 %{SOURCE50} %{buildroot}%{_unitdir}/cpupower.service
+install -m644 %{SOURCE53} %{buildroot}%{_unitdir}/cpupower.path
 install -m644 %{SOURCE51} %{buildroot}%{_sysconfdir}/sysconfig/cpupower
 install -m755 %{SOURCE52} %{buildroot}%{_bindir}/cpupower-start.sh
 %endif
@@ -1953,6 +1957,7 @@ rm -rf %{buildroot}
 %{_libdir}/libcpupower.so.0
 %{_libdir}/libcpupower.so.0.0.0
 %{_unitdir}/cpupower.service
+%{_unitdir}/cpupower.path
 %{_mandir}/man[1-8]/cpupower*
 %config(noreplace) %{_sysconfdir}/sysconfig/cpupower