On Fri, Apr 15, 2022 at 1:59 PM Rex-BC Chen <[email protected]> wrote:
>
> To prevent infinite loop when tracking voltage, we calculate the maximum
> value for each platform data.
> We assume min voltage is 0 and tracking target voltage using
> min_volt_shift for each iteration.
> The retry_max is 3 times of expeted iteration count.
>
> Signed-off-by: Rex-BC Chen <[email protected]>
> ---
> drivers/cpufreq/mediatek-cpufreq.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
> index cc44a7a9427a..d4c00237e862 100644
> --- a/drivers/cpufreq/mediatek-cpufreq.c
> +++ b/drivers/cpufreq/mediatek-cpufreq.c
> @@ -86,6 +86,16 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
> struct regulator *proc_reg = info->proc_reg;
> struct regulator *sram_reg = info->sram_reg;
> int pre_vproc, pre_vsram, new_vsram, vsram, vproc, ret;
> + int retry_max;
> +
> + /*
> + * We assume min voltage is 0 and tracking target voltage using
> + * min_volt_shift for each iteration.
> + * The retry_max is 3 times of expeted iteration count.
> + */
> + retry_max = 3 * DIV_ROUND_UP(max(info->soc_data->sram_max_volt,
> + info->soc_data->proc_max_volt),
> + info->soc_data->min_volt_shift);
mtk_cpufreq_voltage_tracking() will be called very frequently.
retry_max is the same every time mtk_cpufreq_voltage_tracking() is
called. Is it better to calculate before and store in
mtk_cpu_dvfs_info?
>
> pre_vproc = regulator_get_voltage(proc_reg);
> if (pre_vproc < 0) {
> @@ -151,6 +161,12 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
>
> pre_vproc = vproc;
> pre_vsram = vsram;
> +
> + if (--retry_max < 0) {
> + dev_err(info->cpu_dev,
> + "over loop count, failed to set voltage\n");
> + return -EINVAL;
> + }
> } while (vproc != new_vproc || vsram != new_vsram);
>
> return 0;
> --
> 2.18.0
>
Il 15/04/22 08:14, Hsin-Yi Wang ha scritto:
> On Fri, Apr 15, 2022 at 1:59 PM Rex-BC Chen <[email protected]> wrote:
>>
>> To prevent infinite loop when tracking voltage, we calculate the maximum
>> value for each platform data.
>> We assume min voltage is 0 and tracking target voltage using
>> min_volt_shift for each iteration.
>> The retry_max is 3 times of expeted iteration count.
>>
>> Signed-off-by: Rex-BC Chen <[email protected]>
I'm sorry Rex, but this commit has to be squashed with 09/15, as the logic is
that each commit has to be acceptable, and 09/15 is not, without this fix.
Besides, as Hsin-Yi suggested, calculating this every time may hit performance,
but at the same time I don't want to lose this explicit calculation...
>> ---
>> drivers/cpufreq/mediatek-cpufreq.c | 16 ++++++++++++++++
>> 1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
>> index cc44a7a9427a..d4c00237e862 100644
>> --- a/drivers/cpufreq/mediatek-cpufreq.c
>> +++ b/drivers/cpufreq/mediatek-cpufreq.c
>> @@ -86,6 +86,16 @@ static int mtk_cpufreq_voltage_tracking(struct mtk_cpu_dvfs_info *info,
>> struct regulator *proc_reg = info->proc_reg;
>> struct regulator *sram_reg = info->sram_reg;
>> int pre_vproc, pre_vsram, new_vsram, vsram, vproc, ret;
>> + int retry_max;
>> +
>> + /*
>> + * We assume min voltage is 0 and tracking target voltage using
>> + * min_volt_shift for each iteration.
>> + * The retry_max is 3 times of expeted iteration count.
>> + */
>> + retry_max = 3 * DIV_ROUND_UP(max(info->soc_data->sram_max_volt,
>> + info->soc_data->proc_max_volt),
>> + info->soc_data->min_volt_shift);
>
> mtk_cpufreq_voltage_tracking() will be called very frequently.
> retry_max is the same every time mtk_cpufreq_voltage_tracking() is
> called. Is it better to calculate before and store in
> mtk_cpu_dvfs_info?
>
...so I agree with this solution: perhaps you can add a "vtrack_max" variable to
mtk_cpu_dvfs_info as suggested, and fill in that one in function
mtk_cpu_dvfs_info_init(), where we effectively initialize all-the-things.
Cheers,
Angelo