On Fri, Apr 15, 2022 at 1:59 PM Rex-BC Chen <rex-bc.chen@xxxxxxxxxxxx> 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 <rex-bc.chen@xxxxxxxxxxxx>
> ---
> 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
>
