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SubjectRe: [PATCH] ARC: clk: introduce HSDKv1 pll driver
On 08/09, Eugeniy Paltsev wrote:
> On Thu, 2017-08-03 at 18:53 -0700, Stephen Boyd wrote:
> > On 07/14, Eugeniy Paltsev wrote:
> > > + /* input divider = reg.idiv + 1 */
> > > + idiv = 1 + ((val & CGU_PLL_CTRL_IDIV_MASK) >>
> > > CGU_PLL_CTRL_IDIV_SHIFT);
> > > + /* fb divider = 2*(reg.fbdiv + 1) */
> > > + fbdiv = 2 * (1 + ((val & CGU_PLL_CTRL_FBDIV_MASK) >>
> > > CGU_PLL_CTRL_FBDIV_SHIFT));
> > > + /* output divider = 2^(reg.odiv) */
> > > + odiv = 1 << ((val & CGU_PLL_CTRL_ODIV_MASK) >>
> > > CGU_PLL_CTRL_ODIV_SHIFT);
> >
> > Maybe just drop these comments. They're just repeating the code.
>
> Actually I would prefer to keep them, as "2^(reg.odiv)" is more 
> human-readable then
> "1 << ((val & CGU_PLL_CTRL_ODIV_MASK) >> CGU_PLL_CTRL_ODIV_SHIFT)"

Alright.

>
> > > +
> > > + rate = (u64)parent_rate * fbdiv;
> > > + do_div(rate, idiv * odiv);
> > > +
> > > + return rate;
> > > +}
> > > +
> > > +static long hsdk_pll_round_rate(struct clk_hw *hw, unsigned long
> > > rate,
> > > + unsigned long *prate)
> > > +{
> > > + int i;
> > > + long best_rate;
> > > + struct hsdk_pll_clk *clk = to_hsdk_pll_clk(hw);
> > > + const struct hsdk_pll_cfg *pll_cfg = clk->pll_cfg;
> > > +
> > > + if (pll_cfg[0].rate == 0)
> > > + return -EINVAL;
> > 
> > This happens?
>
> Only if we add bad hsdk_pll_cfg table. But it is quite cold code - we
> change pll configuration quite rare, so maybe it's better to keep this
> assert?

Can it be a BUILD_BUG_ON() somehow?

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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