On 18/07/2019 10:45, Jon Hunter wrote:
>
> On 08/07/2019 00:08, Dmitry Osipenko wrote:
>> The PCLK clock is running off SCLK, which is a critical clock that is
>> very unlikely to randomly change its rate. It's also a bit clumsy (and
>> apparently incorrect) to query the clock's rate with interrupts being
>> disabled because clk_get_rate() takes a mutex and that's the case during
>> suspend/cpuidle entering. Lastly, it's better to always fully reprogram
>> PMC state because it's not obvious whether it could be changed after SC7.
>
> I agree with the first part, but I would drop the last sentence because
> I see no evidence of this. Maybe Peter can confirm.
>
>> Signed-off-by: Dmitry Osipenko <dig...@gmail.com>
>> ---
>> drivers/soc/tegra/pmc.c | 26 +++++++++++---------------
>> 1 file changed, 11 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
>> index 9f9c1c677cf4..532e0ada012b 100644
>> --- a/drivers/soc/tegra/pmc.c
>> +++ b/drivers/soc/tegra/pmc.c
>> @@ -1433,6 +1433,7 @@ void tegra_pmc_set_suspend_mode(enum
>> tegra_suspend_mode mode)
>> void tegra_pmc_enter_suspend_mode(enum tegra_suspend_mode mode)
>> {
>> unsigned long long rate = 0;
>> + u64 ticks;
>> u32 value;
>>
>> switch (mode) {
>> @@ -1441,7 +1442,7 @@ void tegra_pmc_enter_suspend_mode(enum
>> tegra_suspend_mode mode)
>> break;
>>
>> case TEGRA_SUSPEND_LP2:
>> - rate = clk_get_rate(pmc->clk);
>> + rate = pmc->rate;
>
> There is another call to clk_get_rate() that could be removed as well.
>
>> break;
>>
>> default:
>> @@ -1451,26 +1452,20 @@ void tegra_pmc_enter_suspend_mode(enum
>> tegra_suspend_mode mode)
>> if (WARN_ON_ONCE(rate == 0))
>> rate = 100000000;
>>
>> - if (rate != pmc->rate) {
>> - u64 ticks;
>> -
>> - ticks = pmc->cpu_good_time * rate + USEC_PER_SEC - 1;
>> - do_div(ticks, USEC_PER_SEC);
>> - tegra_pmc_writel(pmc, ticks, PMC_CPUPWRGOOD_TIMER);
>> -
>> - ticks = pmc->cpu_off_time * rate + USEC_PER_SEC - 1;
>> - do_div(ticks, USEC_PER_SEC);
>> - tegra_pmc_writel(pmc, ticks, PMC_CPUPWROFF_TIMER);
>> + ticks = pmc->cpu_good_time * rate + USEC_PER_SEC - 1;
>> + do_div(ticks, USEC_PER_SEC);
>> + tegra_pmc_writel(pmc, ticks, PMC_CPUPWRGOOD_TIMER);
>
> You could go a step further and update the cpu_good_time/cpu_off_time to
> be ticks and calculated once during probe and recalculated if
> tegra_pmc_set_suspend_mode is called. I am not sure why we really need
> to pass mode to tegra_pmc_enter_suspend_mode() seeing as the mode is
> stored in the pmc struct.
>
>>
>> - wmb();
>> -
>> - pmc->rate = rate;
>> - }
>> + ticks = pmc->cpu_off_time * rate + USEC_PER_SEC - 1;
>> + do_div(ticks, USEC_PER_SEC);
>> + tegra_pmc_writel(pmc, ticks, PMC_CPUPWROFF_TIMER);
>>
>> value = tegra_pmc_readl(pmc, PMC_CNTRL);
>> value &= ~PMC_CNTRL_SIDE_EFFECT_LP0;
>> value |= PMC_CNTRL_CPU_PWRREQ_OE;
>> tegra_pmc_writel(pmc, value, PMC_CNTRL);
>> +
>> + wmb();
I would not move the barrier unless there is a good reason. Maybe it is
intentional that this happens before the other writes.
Jon
--
nvpublic
