Re: [PATCH v3 2/2] cpufreq: tegra: Re-model Tegra cpufreq driver

bilhuang
2013-12-17T10:52:52Z

On 12/17/2013 02:54 PM, Viresh Kumar wrote:
> On 5 December 2013 13:14, Bill Huang <bilhuang@nvidia.com> wrote:
>> Re-model Tegra cpufreq driver to support all Tegra series of SoCs.
>>
>> * Make tegra-cpufreq.c a generic Tegra cpufreq driver.
>> * Move Tegra20 specific codes into tegra20-cpufreq.c.
>> * Bind Tegra cpufreq dirver with a fake device so defer probe would work
>> when we're going to get regulator in the driver to support voltage
>> scaling (DVFS).
>
> I strongly feel we must reuse cpufreq-cpu0 driver here after adding a
> clk/regulator driver for tegra to support all that.

Tegra20 DVFS is a little bit complicated due to the fact that we can't
scale VDD_CPU directly, there are constraints or relationship to other
power rails so I don't think it is a good idea to use generic
cpufreq-cpu0 driver if we're going to support voltage scaling.
>
> @Stephen: If you want we can keep all that tegra specific stuff
> (clk/regulator) in
> tegra-cpufreq.c, but we can easily use cpufreq-cpu0 driver without much
> complications..
>
> I have tried it earlier, got some comments and then got busy in other stuff..
> https://lkml.org/lkml/2013/8/7/364
>
>> static int tegra_cpu_exit(struct cpufreq_policy *policy)
>> {
>> - clk_disable_unprepare(cpu_clk);
>> - clk_disable_unprepare(emc_clk);
>> + cpufreq_frequency_table_cpuinfo(policy, tegra_data->freq_table);
>
> Btw, why do you need this here?
>
Actually the latest version is v4 which is quite different against v3.