Re: [PATCH v0 07/10] phy: freescale: add Samsung HDMI PHY

Lucas Stach
2022-04-11T12:21:48Z

Hi Maxime,

Am Montag, dem 11.04.2022 um 13:59 +0200 schrieb Maxime Ripard:
> Hi Lucas,
>
> On Wed, Apr 06, 2022 at 06:01:20PM +0200, Lucas Stach wrote:
> > +static unsigned long phy_clk_recalc_rate(struct clk_hw *hw,
> > + unsigned long parent_rate)
> > +{
> > + struct fsl_samsung_hdmi_phy *phy = to_fsl_samsung_hdmi_phy(hw);
> > +
> > + if (!phy->cur_cfg)
> > + return 0;
> > +
> > + return phy->cur_cfg->clk_rate;
> > +}
>
> This means that the clock will return 0 at initialization, which will
> throw the rate accounting in the CCF off.
>
> Returning 0 here isn't valid. Surely that phy has a default
> configuration at boot that you could use to initialize a rate?
>
> See https://lore.kernel.org/linux-clk/20220408091037.2041955-1-maxime@cerno.tech/

Thanks for the hint. I don't know the full history of this and surely I
can use the register reset defaults to initialize the clock rate, but
it still seems odd. A powered down clock generator, like the PLL in
this PHY, is not actually putting out a clock at any rate, so 0 for the
rate seems natural, so it's kind of a bad pitfall if the CCF can't deal
with that.

Regards,
Lucas