Re: [PATCH 2/4] cpufreq: add i.MX5 cpufreq driver

[Viresh Kumar <viresh.kumar@linaro.org>]

On 26 May 2014 16:15, Lucas Stach <l.stach@pengutronix.de> wrote:
> This driver handles the i.MX5 specific clock reparenting to be able to
> reprogramm the PLL. cpufreq-cpu0 can only change a postdivider of the
> PLL, which means we can't reach the exact OPP frequencies and can not
> profit from the additional power savings of a slower running PLL.
>
> Also without reprogramming the PLL we could possibly not scale to the
> highest OPPs if the bootloader left the PLL at a slower rate. This is
> the case for many i.MX53 boards, as the CPU regulator normally does
> start up with the voltage required for 800MHz operation. If the
> bootloader decides to not touch the regulator and set the PLL to 800MHz
> the 1GHz and 1.2GHz operating points won't be useable.

Almost all users of cpufreq-cpu0 has such situations and they have
written a clock-driver for "cpu clock" to get this fixed. And they handle
all this PLL stuff in clk_set_rate() for this new clock..

I still couldn't find anything so special here that can't be fixed this way.
There is no point adding and maintaining a cpufreq driver if we can
use cpufreq-cpu0.