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[runtime_pm off]
After Linux starts, it will enable clk and put tempsensor in standby state.
When 'cat /sys/class/hwmon/hwmon0/temp1_input' is executed, will switch to
the run state, and return the value of the sensor after the interrupt is
generated.
$ cat /sys/kernel/debug/clk/clk_summary | grep "temp_sensor"
enable prepare protect duty hardware
clock count count count rate accuracy phase cycle enable
-------------------------------------------------------------------------------------------
u0_temp_sensor_clk_temp 1 1 0 1000000 0 0 50000 Y
u0_temp_sensor_clk_apb0 1 1 0 49500000 0 0 50000 Y
$ cat /sys/class/hwmon/hwmon0/temp1_input
46135
$ cat /sys/class/hwmon/hwmon0/temp1_enable
1
You can 'echo 0 >/sys/class/hwmon/hwmon0/temp1_enable' to turn off the
tempsensor and clk.
$ echo 0 > /sys/class/hwmon/hwmon0/temp1_enable
$ cat /sys/kernel/debug/clk/clk_summary | grep "temp_sensor"
enable prepare protect duty hardware
clock count count count rate accuracy phase cycle enable
-------------------------------------------------------------------------------------------
u0_temp_sensor_clk_temp 0 0 0 1000000 0 0 50000 N
u0_temp_sensor_clk_apb0 0 0 0 49500000 0 0 50000 N
$ cat /sys/class/hwmon/hwmon0/temp1_enable
0
$ cat /sys/class/hwmon/hwmon0/temp1_input
cat: read error: No data available
[runtime_pm on]
When runtime_pm is turned on, sfctemp will automatically enter
the suspend state and close clk after the system is started.
$ cat /sys/kernel/debug/clk/clk_summary | grep "temp_sensor"
enable prepare protect duty hardware
clock count count count rate accuracy phase cycle enable
-------------------------------------------------------------------------------------------
u0_temp_sensor_clk_temp 0 0 0 1000000 0 0 50000 N
u0_temp_sensor_clk_apb0 0 0 0 49500000 0 0 50000 N
when 'cat /sys/class/hwmon/hwmon0/temp1_input', it will call
starfive_temp_resume, enable clk and put sfctemp into power on state.
$ cat /sys/class/hwmon/hwmon0/temp1_input
46235
After the interrupt is generated and the sensor value is obtained, it
will enter the suspend state again. so, hardware-enable-stats is always 'N'.
Of course, in this mode (runtime_pm on), it also supports the opening
and closing of functions (in fact, clk is not directly operated, and the
opening and closing of clk are controlled by runtime_pm)
$ cat /sys/class/hwmon/hwmon0/temp1_input
46235
$ cat /sys/class/hwmon/hwmon0/temp1_enable
1
$ echo 0 > /sys/class/hwmon/hwmon0/temp1_enable
$ cat /sys/class/hwmon/hwmon0/temp1_enable
0
$ cat /sys/class/hwmon/hwmon0/temp1_input
cat: read error: No data available
Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
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