Re: [PATCH v2 3/3] scsi: ufs: core: Add sysfs attributes to control WB buffer resize function

Bart Van Assche
2023-09-08T15:44:09Z

> +What: /sys/bus/platform/drivers/ufshcd/*/enable_wb_buf_resize
> +What: /sys/bus/platform/devices/*.ufs/enable_wb_buf_resize
> +Date: Sept 2023
> +Contact: Lu Hongfei <luhongfei@vivo.com>
> +Description:
> + The host can decrease or increase the WriteBooster Buffer size by setting
> + this file.
> +
> + ====== ======================================
> + 00h Idle (There is no resize operation)
> + 01h Decrease WriteBooster Buffer Size
> + 02h Increase WriteBooster Buffer Size
> + Others Reserved
> + ====== ======================================
> +
> + The file is write only.

The name "enable_wb_buf_resize" seems misleading to me.
"wb_buf_resize_control" is probably a better name for this attribute
since this attribute can be used to increase and decrease the WB buffer
size.

> + if (hba->dev_info.wspecversion < 0x410 ||
> + !hba->dev_info.b_presrv_uspc_en) {
> + dev_err(dev, "The WB buf resize is not allowed!\n");
> + return -EINVAL;
> + }

Please leave out the version number check. There probably will be UFS
4.0 devices that will implement this feature.

Thanks,

Bart.