Re: [PATCH v6 1/6] scsi: ufs: Add "wb_on" sysfs node to control WB on/off

[Bean Huo]

On Tue, 2021-01-19 at 09:01 +0200, Adrian Hunter wrote:
> On 18/01/21 10:10 pm, Bean Huo wrote:
> > From: Bean Huo <beanhuo@xxxxxxxxxx>
> > 
> > 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.

Thanks,
Bean