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

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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



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