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SubjectRe: [PATCH V5 2/2] cpufreq: Tegra: implement intermediate frequency callbacks
From
Viresh,

On Mon, Jun 2, 2014 at 10:19 AM, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> Tegra had always been switching to intermediate frequency (pll_p_clk) since
> ever. CPUFreq core has better support for handling notifications for these
> frequencies and so we can adapt Tegra's driver to it.
>
> Also do a WARN() if clk_set_parent() fails while moving back to pll_x as we
> should have atleast restored to earlier frequency on error.
>
> Tested-by: Stephen Warren <swarren@nvidia.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> drivers/cpufreq/tegra-cpufreq.c | 97 ++++++++++++++++++++++++++---------------
> 1 file changed, 62 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c
> index 6e774c6..a5fbc0a 100644
> --- a/drivers/cpufreq/tegra-cpufreq.c
> +++ b/drivers/cpufreq/tegra-cpufreq.c
> @@ -45,46 +45,51 @@ static struct clk *cpu_clk;
> static struct clk *pll_x_clk;
> static struct clk *pll_p_clk;
> static struct clk *emc_clk;
> +static bool pll_x_prepared;
>
> -static int tegra_cpu_clk_set_rate(unsigned long rate)
> +static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
> + unsigned int index)
> +{
> + unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
> +
> + /*
> + * Don't switch to intermediate freq if:
> + * - we are already at it, i.e. policy->cur == ifreq
> + * - index corresponds to ifreq
> + */
> + if ((freq_table[index].frequency == ifreq) || (policy->cur == ifreq))
> + return 0;
> +
> + return ifreq;
> +}
> +
> +static int tegra_target_intermediate(struct cpufreq_policy *policy,
> + unsigned int index)
> {
> int ret;
>
> /*
> * Take an extra reference to the main pll so it doesn't turn
> - * off when we move the cpu off of it
> + * off when we move the cpu off of it as enabling it again while we
> + * switch to it from tegra_target() would take additional time. Though
> + * when target-freq is intermediate freq, we don't need to take this
> + * reference.

The "Though when target-freq is intermediate freq, we don't need to
take this reference." makes me think that this function is actually
called when target-freq is intermediate freq. I don't think it is,
right?

I don't think that's a huge deal, though and code wise this looks good to me.

Reviewed-by: Doug Anderson <dianders@chromium.org>


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