Re: [PATCH v2 0/8] clk: renesas: rcar-gen2/gen3: Switch to .determine_rate()

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Stephen,

On Wed, Sep 11, 2019 at 6:24 PM Stephen Boyd <sboyd@kernel.org> wrote:
> Quoting Geert Uytterhoeven (2019-09-03 23:51:10)
> > On Wed, Sep 4, 2019 at 12:09 AM Stephen Boyd <sboyd@kernel.org> wrote:
> > > Quoting Geert Uytterhoeven (2019-08-30 06:45:07)
> > > > As the .round_rate() callback returns a long clock rate, it cannot
> > > > return clock rates that do not fit in signed long, but do fit in
> > > > unsigned long.  The newer .determine_rate() callback does not suffer
> > > > from this limitation.  In addition, .determine_rate() provides the
> > > > ability to specify a rate range.
> > > >
> > > > This patch series performs the customary preparatory cleanups, and
> > > > switches the Z (CPU) and SD clocks in the R-Car Gen2 and Gen3 clock
> > > > drivers from the .round_rate() to the .determine_rate() callback.
> > > > Note that the "div6" clock driver hasn't been converted yet, so div6
> > > > clocks still use .round_rate().
> > > >
> > > > Changes compared to v1[1]:
> > > >   - Add preparatory arithmetic division improvements
> > > >   - Split off cpg_sd_clock_calc_div() absorption and SD clock best rate
> > > >     calculation,
> > > >   - Use div_u64() for division by unsigned long,
> > > >
> > > > This has been tested on R-Car M2-W and various R-Car Gen3, and should
> > > > have no behavioral impact.
> > >
> > > From what I recall the rate range code is broken but I can't remember
> > > how. Anyway, I was just curious if you ran into any issues with that
> > > code.
> >
> > I didn't ran into any issues.  But please note that in all tested cases, the
> > limits were 0 and ULONG_MAX anyway, so probably it didn't trigger the
> > broken cases in the rate range code.
> >
> > So, is it good to have .determine_rate() support in individual clock drivers
> > now, or do you want me to postpone the last 3 patches of my series until the
> > rate range code is fixed?
> >
>
> It's fine to use .determine_rate() because we'll fix the problems in the
> clk framework. So no concern from me here. Just curious if you ran into
> any problems.

Thanks, queued in clk-renesas-for-v5.5.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds