Hi Can, On Wed, 2020-02-19 at 18:33 +0800, Can Guo wrote: > Hi Stanley, > > On 2020-02-19 17:11, Stanley Chu wrote: > > Hi Can, > > > > On Wed, 2020-02-19 at 10:35 +0800, Can Guo wrote: > > > >> Since we all need this delay here, how about put the delay in the > >> entrence of ufshcd_setup_clocks(), before vops_setup_clocks()? > >> If so, we can remove all the delays we added in our vops since the > >> delay anyways delays everything inside ufshcd_setup_clocks(). > >> > > > > Always putting the delay in the entrance of ufshcd_setup_clocks() may > > add unwanted delay for vendors, just like your current implementation, > > or some other vendors who do not want to disable the reference clock. > > > > I think current patch is more reasonable because the delay is applied > > to > > clock only named as "ref_clk" specifically. > > > > If you needs to keep "ref_clk" in DT, would you consider to remove the > > delay in your ufs_qcom_dev_ref_clk_ctrl() and let the delay happens via > > common ufshcd_setup_clocks() only? However you may still need delay if > > call path comes from ufs_qcom_pwr_change_notify(). > > > > What do you think? > > > > I agree current change is more reasonable from what it looks, but the > fact > is that I canont remove the delay in ufs_qcom_dev_ref_clk_ctrl() even > with > this change. On our platforms, ref_clk in DT serves multipule purposes, > the ref_clk provided to UFS device is actually controlled in > ufs_qcom_dev_ref_clk_ctrl(), which comes before where this change kicks > start, > so if I remove the delay in ufs_qcom_dev_ref_clk_ctrl(), this change > cannot > provide us the correct delay before gate the ref_clk provided to UFS > device. > > Always putting the delay in the entrance of ufshcd_setup_clocks() may > > add unwanted delay for vendors, just like your current implementation, > > or some other vendors who do not want to disable the reference clock. > > I meant if we put the delay in the entrance, I will be able to remove > the delay in ufs_qcom_dev_ref_clk_ctrl(). Meanwhile, we can add proper > checks before the delay to make sure it is initiated only if ref_clk > needs > to be disabled, i.e: > > if(!on && !skip_ref_clk && hba->dev_info.clk_gating_wait_us) > usleep_range(); > > Does this look better to you? Firstly thanks so much for above details. Again this statement may also add unwanted delay if some other vendors does not have "ref_clk" in DT or they don't/can't disable the reference clock provided to UFS device. > > Anyways, we will see regressions with this change on our platforms, can > we > have more discussions before get it merged? It should be OK if you go > with > patch #2 alone first, right? Thanks. Now the fact is that this change will impact your flow and it seems no solid conclusion yet. Sure I could drop patch #1 and submit patch #2 only first : ) Thanks, Stanley Chu
