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Date: Mon, 17 Feb 2020 21:42:35 +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 21:34, Stanley Chu wrote: > Hi Can, > > On Mon, 2020-02-17 at 21:22 +0800, Can Guo wrote: >> 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? > > MediaTek driver is not using reference clocks named as "ref_clk" > defined > in device tree, thus the delay specific for "ref_clk" in > ufshcd_setup_clocks() will not be applied in MediaTek platform. > > This patch is aimed to add delay for this kind of "ref_clk" used by any > future vendors. > > Anyway thanks for the reminding : ) > >> >> Thanks, >> Can Guo. > > > Thanks, > Stanley Hi Stanley, Then we are unluckily hit by this change. We have ref_clk in DT, thus this change would add unwanted delays to our platforms. but still we disable device's ref_clk in vops. :) Could you please hold on patch #1 first? I need sometime to have a dicussion with my colleagues on this. Thanks. Can Guo.
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