On Thu, Aug 08, 2019 at 04:46:51PM -0700, Sowjanya Komatineni wrote:
> This patch adds suspend and resume pm ops for cpufreq driver.
>
> PLLP is the safe clock source for CPU during system suspend and
> resume as PLLP rate is below the CPU Fmax at Vmin.
>
> CPUFreq driver suspend switches the CPU clock source to PLLP and
> disables the DFLL clock.
>
> During system resume, warmboot code powers up the CPU with PLLP
> clock source. So CPUFreq driver resume enabled DFLL clock and
> switches CPU back to DFLL clock source.
>
> Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Reviewed-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> ---
> drivers/cpufreq/tegra124-cpufreq.c | 60 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 60 insertions(+)
>
> diff --git a/drivers/cpufreq/tegra124-cpufreq.c b/drivers/cpufreq/tegra124-cpufreq.c
> index 4f0c637b3b49..e979a3370988 100644
> --- a/drivers/cpufreq/tegra124-cpufreq.c
> +++ b/drivers/cpufreq/tegra124-cpufreq.c
> @@ -6,6 +6,7 @@
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>
> #include <linux/clk.h>
> +#include <linux/cpufreq.h>
> #include <linux/err.h>
> #include <linux/init.h>
> #include <linux/kernel.h>
> @@ -128,8 +129,67 @@ static int tegra124_cpufreq_probe(struct platform_device *pdev)
> return ret;
> }
>
> +static int __maybe_unused tegra124_cpufreq_suspend(struct device *dev)
> +{
> + struct tegra124_cpufreq_priv *priv = dev_get_drvdata(dev);
> + int err;
> +
> + /*
> + * PLLP rate 408Mhz is below the CPU Fmax at Vmin and is safe to
> + * use during suspend and resume. So, switch the CPU clock source
> + * to PLLP and disable DFLL.
> + */
> + err = clk_set_parent(priv->cpu_clk, priv->pllp_clk);
> + if (err < 0) {
> + dev_err(dev, "failed to reparent to PLLP: %d\n", err);
> + return err;
> + }
> +
> + /* disable DFLL clock */
> + clk_disable_unprepare(priv->dfll_clk);
This comment is superfluous since it doesn't explain anything that the
code below doesn't explain already.
Not sure who will end up merging this. If not me, then this is:
Acked-by: Thierry Reding <treding@xxxxxxxxxx>
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