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 <digetx@xxxxxxxxx>
> ---
> 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();
> }
> #endif
>
> @@ -2082,6 +2077,7 @@ static int tegra_pmc_probe(struct platform_device *pdev)
> pmc->clk = NULL;
> }
>
> + pmc->rate = clk_get_rate(pmc->clk);
You should check the value returned is not 0 here.
Cheers
Jon
--
nvpublic
