Re: [PATCH v2 0/7] usb: dwc3: Calculate REFCLKPER et. al. from reference clock

[Sean Anderson]

Hi Baruch,

On 1/19/22 1:14 PM, Baruch Siach wrote:
> Hi Sean,
>
> On Tue, Jan 18 2022, Sean Anderson wrote:
> > This is a rework of patches 3-5 of [1]. It attempts to correctly program
> > REFCLKPER and REFCLK_FLADJ based on the reference clock frequency. Since
> > we no longer need a special property duplicating this configuration,
> > snps,ref-clock-period-ns is deprecated.
> >
> > Please test this! Patches 3/4 in this series have the effect of
> > programming REFCLKPER and REFCLK_FLADJ on boards which already configure
> > the "ref" clock. I have build tested, but not much else.
>
> Tested here on IPQ6010 based system. USB still works. But the with "ref"
> clock at 24MHz, period is calculated as 0x29. Previous
> snps,ref-clock-period-ns value used to be 0x32.
>
> Is that expected?

Yes. From the documentation for GFLADJ_REFCLK_240MHZ_DECR:

> Examples:
> If the ref_clk is 24 MHz then
> - GUCTL.REF_CLK_PERIOD = 41
> - GFLADJ.GFLADJ_REFCLK_240MHZ_DECR = 240/24 = 10

And 41 == 0x29.

--Sean