[PATCH v3 2/6] clk: renesas: rcar-gen3: Add Z2 clock divider support

[Geert Uytterhoeven]

Hi Simon,

On Mon, Oct 9, 2017 at 10:02 AM, Geert Uytterhoeven
<geert at linux-m68k.org> wrote:
> On Thu, Oct 5, 2017 at 3:23 PM, Simon Horman <horms+renesas at verge.net.au> wrote:
>> From: Takeshi Kihara <takeshi.kihara.df at renesas.com>
>>
>> This patch adds Z2 clock divider support for R-Car Gen3 SoC.
>>
>> Signed-off-by: Takeshi Kihara <takeshi.kihara.df at renesas.com>
>> Signed-off-by: Simon Horman <horms+renesas at verge.net.au>
>> ---
>> v2 [Simon Horman]
>> * Consolidate Z and Z2 clock ops
>> * Allow setting of Z2 clock
>
> Thanks for the update!
>
>> --- a/drivers/clk/renesas/rcar-gen3-cpg.c
>> +++ b/drivers/clk/renesas/rcar-gen3-cpg.c
>
>> @@ -88,8 +90,8 @@ static int cpg_z_clk_set_rate(struct clk_hw *hw, unsigned long rate,
>>         if (clk_readl(zclk->kick_reg) & CPG_FRQCRB_KICK)
>>                 return -EBUSY;
>>
>> -       val = clk_readl(zclk->reg) & ~CPG_FRQCRC_ZFC_MASK;
>> -       val |= FIELD_PREP(CPG_FRQCRC_ZFC_MASK, 32 - mult);
>> +       val = clk_readl(zclk->reg) & ~zclk->mask;
>> +       val |= ((32 - mult) << __bf_shf(zclk->mask)) & zclk->mask;
>
> Any special reason you're now open coding FIELD_PREP()?

Now I know: to circumvent the
BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), ...) in
__BF_FIELD_CHECK(), called from FIELD_PREP().

Given <linux/bitfield.h> is intended to work with constant masks
only, I think it's best to not use it, and replace __bf_shf() by __ffs().

> Reviewed-by: Geert Uytterhoeven <geert+renesas at glider.be>

Oops, looks like you forgot to replace CPG_FRQCRC_ZFC_MASK in
cpg_z_clk_recalc_rate() by zclk->mask.
Sorry for missing that.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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