Re: [PATCH v6 1/6] scsi: ufs: Add "wb_on" sysfs node to control WB on/off
From: Adrian Hunter <adrian.hunter@intel.com>
Date: 2021-01-19 10:26:07
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On 19/01/21 11:33 am, Bean Huo wrote:
On Tue, 2021-01-19 at 09:01 +0200, Adrian Hunter wrote:quoted
On 18/01/21 10:10 pm, Bean Huo wrote:quoted
From: Bean Huo <redacted> Currently UFS WriteBooster driver uses clock scaling up/down to set WB on/off, for the platform which doesn't support UFSHCD_CAP_CLK_SCALING, WB will be always on. Provide a sysfs attribute to enable/disable WB during runtime. Write 1/0 to "wb_on" sysfs node to enable/disable UFS WB.Is it so, that after a full reset, WB is always enabled again? Is that intended?Hello Adrian Good questions. yes, after a full reset, the UFS device side by default is wb disabled, then WB will be always enabled agaion in ufshcd_wb_config(hba). but, for the platform which supports UFSHCD_CAP_CLK_SCALING, wb will be disabled again while clk scaling down and enabled while clk scaling up. Regarding the last question, I think OEM wants to do that. maybe they suppose there will be a lot of writing after reset?? From the UFS device's point of view, the control of WB is up to the user.
If it is by design enabled after reset, then perhaps it should be mentioned in the sysfs documentation.