Re: [PATCH V4 3/3] cpufreq: Tegra: implement intermediate frequency callbacks

Stephen Warren
2014-05-22T16:40:01Z

On 05/21/2014 02:59 AM, Viresh Kumar 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.

> diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c

> @@ -98,10 +96,23 @@ static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
> else
> clk_set_rate(emc_clk, 100000000); /* emc 50Mhz */
>
> - ret = tegra_cpu_clk_set_rate(rate * 1000);
> + /* target freq == pll_p */
> + if (rate * 1000 == clk_get_rate(pll_p_clk)) {
> + ret = tegra_target_intermediate(policy, index);
> + goto disable_pll_x;
> + }

I think the call to tegra_target_intermediate() is wrong here; shouldn't
the cpufreq core guarantee that tegra_target_intermediate() has always
been called before tegra_target(), so there's no need to repeat that
call here?

Also, tegra_target() doesn't seem to follow the rule documented by patch
2/3 that states ->target() should restore the orignal frequency on
error. I'm not even sure if that's possible in general.