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

Chen-Yu Tsai
2014-09-27T07:23:05Z

On Sat, Sep 27, 2014 at 3:07 PM, Maxime Ripard
<maxime.ripard@free-electrons.com> wrote:
> On Wed, Sep 24, 2014 at 11:35:58PM +0800, Chen-Yu Tsai wrote:
>> 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?
>
> If Emilio prefers to have a single clock node, fine. But please update
> the DT bindings documentation.

OK. Then this series needs a bit of work. I'll pick the orignal
divs clocks patch from patchwork (as I didn't keep one) and fix
up the DT.

ChenYu