[PATCH 1/7] clk: sunxi: Add post clk divider for factor clocks

Chen-Yu Tsai
2014-09-24T15:35:58Z

Hi Maxime, Emilio,

On Tue, Sep 16, 2014 at 11:57 PM, Maxime Ripard
<maxime.ripard@free-electrons.com> wrote:
> Hi Emilio,
>
> On Sat, Sep 13, 2014 at 11:43:46AM -0300, Emilio L?pez wrote:
>> Hi,
>>
>> El 06/09/14 a las 07:47, Chen-Yu Tsai escibi?:
>> >Some factor clocks, mostly PLLs, have an extra fixed divider just before
>> >the clock output. Add an option to the factor clk driver config data to
>> >specify this divider.
>> >
>> >Signed-off-by: Chen-Yu Tsai <wens@csie.org>
>> >---
>> > drivers/clk/sunxi/clk-factors.c | 3 +++
>> > drivers/clk/sunxi/clk-factors.h | 1 +
>> > 2 files changed, 4 insertions(+)
>> >
>> >diff --git a/drivers/clk/sunxi/clk-factors.c b/drivers/clk/sunxi/clk-factors.c
>> >index 2057c8a..435111d 100644
>> >--- a/drivers/clk/sunxi/clk-factors.c
>> >+++ b/drivers/clk/sunxi/clk-factors.c
>> >@@ -64,6 +64,9 @@ static unsigned long clk_factors_recalc_rate(struct clk_hw *hw,
>> > /* Calculate the rate */
>> > rate = (parent_rate * (n + config->n_start) * (k + 1) >> p) / (m + 1);
>> >
>> >+ if (config->post_div)
>> >+ rate /= config->post_div;
>> >+
>> > return rate;
>> > }
>> >
>> >diff --git a/drivers/clk/sunxi/clk-factors.h b/drivers/clk/sunxi/clk-factors.h
>> >index d2d0efa..ce70c65 100644
>> >--- a/drivers/clk/sunxi/clk-factors.h
>> >+++ b/drivers/clk/sunxi/clk-factors.h
>> >@@ -16,6 +16,7 @@ struct clk_factors_config {
>> > u8 pshift;
>> > u8 pwidth;
>> > u8 n_start;
>> >+ u8 post_div;
>> > };
>> >
>> > struct clk_factors {
>> >
>>
>> For the record, I liked your solution on[1] more, as it's in line
>> with what we're doing on the other sunxi platforms, instead of
>> adding features in factors to cover for some cases. But it's your
>> and Maxime's call, as I haven't written any of the sun6i code so
>> far.
>
> No, you still wrote most of the clock support, so your opinion is
> always valuable (and valued).
>
> Thing is, unlike what was done in the sun4i driver where there was a
> "real" technical issue that was preventing us from using only
> fixed-factor, we're not in such a case in sun6i (and later,
> apparently).
>
> PLL6 has only one output, which is then directly multiplied by
> fixed-factors, without any (pre|post)-dividers for any of them.
>
> That means that following what you did for the sun4i would just
> register 3 "dumbs" fixed-factors, that we couldn't reference from DT,
> or through a cryptic index (which is not even documented in our
> bindings).
>
> I'd be fine either way, I just prefer the solution that has less code
> and is more explicit.

What's the verdict on this series?

ChenYu