RE:(2) [PATCH v4 4/7] scsi: ufs: wb: Add explicit flush sysfs attribute

[Jinyoung CHOI <j-young.choi@samsung.com>]

>> There is the following quirk to bypass "WB Flush" in Write Booster.
>> 
>>         - UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL
>> 
>> If this quirk is not set, there is no knob that can control "WB
>> Flush".
>
>> 
>> There are three flags that control Write Booster Feature.
>>         1. WB ON/OFF
>>         2. WB Hibern Flush ON/OFF (implicitly)
>>         3. WB Flush ON/OFF (explicit)
>> 
>> The sysfs attribute that controls the WB was implemented. (1)
>> 
>> In the case of "Hibern Flush", it is always good to turn on.
>> Control may not be required. (2)
>> 
>> Finally, "Flush" may be necessary because the Auto-Hibern8 is not
>> supported in a specific environment.
>> So the sysfs attribute that controls this is necessary. (3)
>> 
>> Reviewed-by: Avri Altman <avri.altman@wdc.com>
>> Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
>> ---
>...
>> 
>> +static ssize_t wb_buf_flush_en_store(struct device *dev,
>> +                                    struct device_attribute *attr,
>> +                                    const char *buf, size_t count)
>> +{
>> +       struct ufs_hba *hba = dev_get_drvdata(dev);
>> +       unsigned int wb_buf_flush_en;
>> +       ssize_t res;
>> +
>> +       if (ufshcd_is_wb_allowed(hba) &&
>> +          !(hba->quirks & UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL)) {
>> +               dev_warn(dev, "It is not allowed to configure WB buf
>> flush!\n");
>> +               return -EOPNOTSUPP;
>> +       }
>> +
>Hi J-young,
>
>I don't understand here, if UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL is
>not set (manual flush is not disable), so we cannot manually flush
>buffer? or should we check if Auto-Hibern8 is supported?
>
>Kind regards,
>Bean

Hi Bean, 
As the patch was separated, the conditional sentence went wrong.
Thank you for checking. I will modify it quickly.

Thanks,
Jinyoung.