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

From: Can Guo
Date: Mon Feb 17 2020 - 08:22:56 EST

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?

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.

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?

Can Guo.