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Date: Mon, 17 Feb 2020 20:58:20 +0800 From: Can Guo <cang@...eaurora.org> To: Stanley Chu <stanley.chu@...iatek.com> Cc: linux-scsi@...r.kernel.org, martin.petersen@...cle.com, avri.altman@....com, alim.akhtar@...sung.com, jejb@...ux.ibm.com, beanhuo@...ron.com, asutoshd@...eaurora.org, matthias.bgg@...il.com, bvanassche@....org, linux-mediatek@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, kuohong.wang@...iatek.com, peter.wang@...iatek.com, chun-hung.wu@...iatek.com, andy.teng@...iatek.com Subject: Re: [PATCH v1 1/2] scsi: ufs: add required delay after gating reference clock On 2020-02-17 17:35, Stanley Chu wrote: > In UFS version 3.0, a newly added attribute bRefClkGatingWaitTime > defines > the minimum time for which the reference clock is required by device > during > transition to LS-MODE or HIBERN8 state. > > Currently this time is detected and stored in > hba->dev_info.clk_gating_wait_us but applied to vendor implementatios > only. > Make it applied to reference clock named as "ref_clk" in device tree in > common path. > > Signed-off-by: Stanley Chu <stanley.chu@...iatek.com> > --- > drivers/scsi/ufs/ufshcd.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index 744b8254220c..7f60721f54d1 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -7417,8 +7417,10 @@ static int __ufshcd_setup_clocks(struct ufs_hba > *hba, bool on, > struct ufs_clk_info *clki; > struct list_head *head = &hba->clk_list_head; > unsigned long flags; > + unsigned long wait_us; > ktime_t start = ktime_get(); > bool clk_state_changed = false; > + bool ref_clk; > > if (list_empty(head)) > goto out; > @@ -7436,7 +7438,8 @@ static int __ufshcd_setup_clocks(struct ufs_hba > *hba, bool on, > > list_for_each_entry(clki, head, list) { > if (!IS_ERR_OR_NULL(clki->clk)) { > - if (skip_ref_clk && !strcmp(clki->name, "ref_clk")) > + ref_clk = !strcmp(clki->name, "ref_clk") ? true : false; > + if (skip_ref_clk && ref_clk) > continue; > > clk_state_changed = on ^ clki->enabled; > @@ -7449,6 +7452,9 @@ static int __ufshcd_setup_clocks(struct ufs_hba > *hba, bool on, > } > } 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 Stanley, 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. > } > clki->enabled = on; > dev_dbg(hba->dev, "%s: clk: %s %sabled\n", __func__,
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