Hi Guenter,
On Fri, 9 Apr 2021 10:48:51 -0700, Guenter Roeck wrote:
> The driver implements two separate functions to read and update
> energy values. One function is called periodically and updates
> cached enery information to avoid loss of data, the other reads
> energy data on demand to report it to userspace. The second
> function reads current energy data, adds the difference to the
> data previously obtained by the first function, and then discards
> the updated data.
>
> Simplify the code and always call the first function, then report
> the energy data obtained by this function to userspace.
I like the idea.
> Cc: Naveen Krishna Chatradhi <nchatrad@xxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> v2: Added patch, simplification
>
> drivers/hwmon/amd_energy.c | 31 ++++++-------------------------
> 1 file changed, 6 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/hwmon/amd_energy.c b/drivers/hwmon/amd_energy.c
> index a86cc8d6d93d..93bad64039f1 100644
> --- a/drivers/hwmon/amd_energy.c
> +++ b/drivers/hwmon/amd_energy.c
> @@ -118,35 +118,12 @@ static void read_accumulate(struct amd_energy_data *data)
> data->core_id++;
> }
>
> -static void amd_add_delta(struct amd_energy_data *data, int ch,
> - int cpu, long *val, u32 reg)
> -{
> - struct sensor_accumulator *accum;
> - u64 input;
> -
> - mutex_lock(&data->lock);
> - rdmsrl_safe_on_cpu(cpu, reg, &input);
> - input &= AMD_ENERGY_MASK;
> -
> - accum = &data->accums[ch];
> - if (input >= accum->prev_value)
> - input += accum->energy_ctr -
> - accum->prev_value;
> - else
> - input += UINT_MAX - accum->prev_value +
> - accum->energy_ctr;
> -
> - /* Energy consumed = (1/(2^ESU) * RAW * 1000000UL) μJoules */
> - *val = div64_ul(input * 1000000UL, BIT(data->energy_units));
> -
> - mutex_unlock(&data->lock);
> -}
> -
> static int amd_energy_read(struct device *dev,
> enum hwmon_sensor_types type,
> u32 attr, int channel, long *val)
> {
> struct amd_energy_data *data = dev_get_drvdata(dev);
> + struct sensor_accumulator *accum;
> u32 reg;
> int cpu;
>
> @@ -162,7 +139,11 @@ static int amd_energy_read(struct device *dev,
>
> reg = ENERGY_CORE_MSR;
> }
> - amd_add_delta(data, channel, cpu, val, reg);
> +
> + accumulate_delta(data, channel, cpu, reg);
> + accum = &data->accums[channel];
> +
> + *val = div64_ul(accum->energy_ctr * 1000000UL, BIT(data->energy_units));
Is it considered safe to read accum->energy_ctr while not holding
data->lock?
>
> return 0;
> }
If the answer to the question above is "yes" then:
Reviewed-by: Jean Delvare <jdelvare@xxxxxxx>
--
Jean Delvare
SUSE L3 Support
