Messages in this thread | | | Date | Fri, 15 Apr 2022 14:24:11 +0200 | Subject | Re: [PATCH V3 10/15] cpufreq: mediatek: Add counter to prevent infinite loop when tracking voltage | From | AngeloGioacchino Del Regno <> |
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Il 15/04/22 08:14, Hsin-Yi Wang ha scritto: > On Fri, Apr 15, 2022 at 1:59 PM Rex-BC Chen <rex-bc.chen@mediatek.com> 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@mediatek.com>
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
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