Re: [PATCH v3 4/6] clk: qcom: clk-rcg2: don't re-search config on rcg2_set_rate

[Dmitry Baryshkov]

On 29/03/2023 22:52, Stephen Boyd wrote:
> Quoting Christian Marangi (2023-01-17 05:54:57)
> > Currently the rcg2 driver search the rate to apply 2 times.
> > - In _freq_tbl_determine_rate for the determine_rate function used by
> >    core clk to understand the best rate to set with set_rate
> > - In rcg2_set_rate where the suggested rate is not trusted and searched
> >    another time using a CEIL or FLOOR policy.
> >
> > This is fundamentally wrong as we are ignoring what core clock is
> > deciding and just setting whatever clock configuration we want for the
> > suggested clock. The problem is in the fact that the correct clock
> > should have already be searched and selected with the determine_rate
> > function and set_rate should just apply whatever clock was provided.
>
> It sounds like you're assuming the rate coming into the set_rate clk_op
> is rounded? Don't make that assumption. The set_rate clk_op should round
> the rate again. The parent rate could have changed.

My fault, I suggested this some time ago on the basis that... "CCF 
switching the parent rate during the clk_set_rate() call. Then the 
second lookup might end up selecting different parent/mnd configuration."

--
With best wishes
Dmitry