[PATCH 1/8] clk: sunxi: factors: Add m_start parameters

[Maxime Ripard]

On Thu, May 14, 2015 at 05:12:07PM +0800, Chen-Yu Tsai wrote:
> On Sat, May 2, 2015 at 7:24 PM, Maxime Ripard
> <maxime.ripard at free-electrons.com> wrote:
> > Some clocks start incrementing the m factor at 0. Add a parameter to handle
> > it just like we did for the N factor.
> >
> > Since the behaviour until now was to assume that the m factor was starting
> > at 1, we also need to fix the other users.
> >
> > Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>
> > ---
> >  drivers/clk/sunxi/clk-factors.c    | 11 ++++++++++-
> >  drivers/clk/sunxi/clk-factors.h    |  2 ++
> >  drivers/clk/sunxi/clk-mod0.c       |  2 ++
> >  drivers/clk/sunxi/clk-sun8i-mbus.c |  2 ++
> >  drivers/clk/sunxi/clk-sun9i-core.c |  6 ++++++
> >  drivers/clk/sunxi/clk-sunxi.c      | 10 ++++++++++
> >  6 files changed, 32 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/clk/sunxi/clk-factors.c b/drivers/clk/sunxi/clk-factors.c
> > index 8c20190a3e9f..100a711c3e3d 100644
> > --- a/drivers/clk/sunxi/clk-factors.c
> > +++ b/drivers/clk/sunxi/clk-factors.c
> > @@ -56,15 +56,24 @@ static unsigned long clk_factors_recalc_rate(struct clk_hw *hw,
> >         /* Get each individual factor if applicable */
> >         if (config->nwidth != SUNXI_FACTORS_NOT_APPLICABLE)
> >                 n = FACTOR_GET(config->nshift, config->nwidth, reg);
> > +
> >         if (config->kwidth != SUNXI_FACTORS_NOT_APPLICABLE)
> >                 k = FACTOR_GET(config->kshift, config->kwidth, reg);
> > +
> >         if (config->mwidth != SUNXI_FACTORS_NOT_APPLICABLE)
> >                 m = FACTOR_GET(config->mshift, config->mwidth, reg);
> > +       else
> > +               /* Make sure we don't get a division by zero */
> > +               m = 1;
> 
> What happens when mwidth is valid, m_start = 0, and m = 0?

That's a very good question. A division by zero in the kernel, I'd
say.

But I don't think we can end up in such a case today, and it's
somewhat expected that it will happen, and no clock have looked at can
actually end up in such a case.

> Other than that, this one looks good.

Thanks!

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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