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Date:   Tue, 15 Dec 2020 11:32:00 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Bean Huo <huobean@gmail.com>
Cc:     alim.akhtar@samsung.com, avri.altman@wdc.com,
        asutoshd@codeaurora.org, jejb@linux.ibm.com,
        martin.petersen@oracle.com, stanley.chu@mediatek.com,
        beanhuo@micron.com, bvanassche@acm.org, tomas.winkler@intel.com,
        cang@codeaurora.org, linux-scsi@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/6] scsi: ufs: Add "wb_on" sysfs node to control WB
 on/off
Message-ID: <X9iQoIpL48yQyr7D@kroah.com>
References: <20201211140035.20016-1-huobean@gmail.com>
 <20201211140035.20016-2-huobean@gmail.com>
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On Fri, Dec 11, 2020 at 03:00:30PM +0100, Bean Huo wrote:
> From: Bean Huo <beanhuo@micron.com>
> 
> 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.
> 
> Reviewed-by: Avri Altman <avri.altman@wdc.com>
> Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
> Signed-off-by: Bean Huo <beanhuo@micron.com>
> ---
>  drivers/scsi/ufs/ufs-sysfs.c | 41 ++++++++++++++++++++++++++++++++++++
>  drivers/scsi/ufs/ufshcd.c    |  3 +--
>  drivers/scsi/ufs/ufshcd.h    |  2 ++
>  3 files changed, 44 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-sysfs.c
> index 08e72b7eef6a..2b4e9fe935cc 100644
> --- a/drivers/scsi/ufs/ufs-sysfs.c
> +++ b/drivers/scsi/ufs/ufs-sysfs.c
> @@ -189,6 +189,45 @@ static ssize_t auto_hibern8_store(struct device *dev,
>  	return count;
>  }
>  
> +static ssize_t wb_on_show(struct device *dev, struct device_attribute *attr,
> +			  char *buf)
> +{
> +	struct ufs_hba *hba = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", hba->wb_enabled);

Please just use sysfs_emit().

> +}
> +
> +static ssize_t wb_on_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_enable;
> +	ssize_t res;
> +
> +	if (ufshcd_is_clkscaling_supported(hba)) {
> +		/*
> +		 * If the platform supports UFSHCD_CAP_AUTO_BKOPS_SUSPEND,
> +		 * turn WB on/off will be done while clock scaling up/down.
> +		 */
> +		dev_warn(dev, "To control WB through wb_on is not allowed!\n");
> +		return -EOPNOTSUPP;
> +	}
> +	if (!ufshcd_is_wb_allowed(hba))
> +		return -EOPNOTSUPP;
> +
> +	if (kstrtouint(buf, 0, &wb_enable))
> +		return -EINVAL;
> +
> +	if (wb_enable != 0 && wb_enable != 1)
> +		return -EINVAL;
> +
> +	pm_runtime_get_sync(hba->dev);
> +	res = ufshcd_wb_ctrl(hba, wb_enable);
> +	pm_runtime_put_sync(hba->dev);
> +
> +	return res < 0 ? res : count;
> +}

Where is the new Documentation/ABI/ update for this new sysfs file you
are adding?

thanks,

greg k-h