Re: [PATCH v1 1/2] scsi: ufs: add required delay after gating reference clock

Can Guo
2020-02-17T13:22:58Z

On 2020-02-17 21:12, Stanley Chu wrote:
> Hi Can,
>
>
>> > } else if (!on && clki->enabled) {
>> > clk_disable_unprepare(clki->clk);
>> > + wait_us = hba->dev_info.clk_gating_wait_us;
>> > + if (ref_clk && wait_us)
>> > + usleep_range(wait_us, wait_us + 10);
>>
>> Hi St,anley,
>>
>> If wait_us is 1us, it would be inappropriate to use usleep_range()
>> here.
>> You have checks of the delay in patch #2, but why it is not needed
>> here?
>>
>> Thanks,
>> Can Guo.
>
> You are right. I could make that delay checking as common function so
> it
> can be used here as well to cover all possible values.
>
> Thanks for suggestion.
> Stanley

Hi Stanley,

One more thing, as in patch #2, you have already added delays in your
ufshcd_vops_setup_clocks(OFF, PRE_CHANGE) path, plus this delay here,
don't you delay for 2*bRefClkGatingWaitTime in ufshcd_setup_clocks()?
As the delay added in your vops also delays the actions of turning
off all the other clocks in ufshcd_setup_clocks(), you don't need the
delay here again, do you agree?

Thanks,
Can Guo.