Re: [PATCH v6] ufs: core: print UFSHCD capabilities in controller's sysfs node

Greg Kroah-Hartman
2022-08-03T06:12:18Z

On Wed, Aug 03, 2022 at 07:50:07AM +1000, Daniil Lunev wrote:
> Allows userspace to check if Clock Scaling and Write Booster are
> supported.
>
> Signed-off-by: Daniil Lunev <dlunev@chromium.org>
>
> ---
>
> Changes in v6:
> * Add comment to clarify meaning of the "capbilities" sysfs group.
>
> Changes in v5:
> * Correct wording for clock scaling.
> * Correct wording for the commit message.
>
> Changes in v4:
> * Dropped crypto node per Eric Biggers mentioning it can be queried from
> disk's queue node
>
> Changes in v3:
> * Expose each capability individually.
> * Update documentation to represent new scheme.
>
> Changes in v2:
> * Add documentation entry for the new sysfs node.
>
> Documentation/ABI/testing/sysfs-driver-ufs | 26 +++++++++++++++
> drivers/ufs/core/ufs-sysfs.c | 37 ++++++++++++++++++++++
> 2 files changed, 63 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-ufs b/Documentation/ABI/testing/sysfs-driver-ufs
> index 6b248abb1bd71..1750a9b84ce0f 100644
> --- a/Documentation/ABI/testing/sysfs-driver-ufs
> +++ b/Documentation/ABI/testing/sysfs-driver-ufs
> @@ -1591,6 +1591,32 @@ Description: This entry shows the status of HPB.
>
> The file is read only.
>
> +What: /sys/bus/platform/drivers/ufshcd/*/capabilities/clock_scaling
> +What: /sys/bus/platform/devices/*.ufs/capabilities/clock_scaling
> +Date: July 2022
> +Contact: Daniil Lunev <dlunev@chromium.org>
> +Description: Indicates status of clock scaling.
> +
> + == ============================
> + 0 Clock scaling is not supported.
> + 1 Clock scaling is supported.
> + == ============================
> +
> + The file is read only.
> +
> +What: /sys/bus/platform/drivers/ufshcd/*/capabilities/write_booster
> +What: /sys/bus/platform/devices/*.ufs/capabilities/write_booster
> +Date: July 2022
> +Contact: Daniil Lunev <dlunev@chromium.org>
> +Description: Indicates status of Write Booster.
> +
> + == ============================
> + 0 Write Booster can not be enabled.
> + 1 Write Booster can be enabled.
> + == ============================
> +
> + The file is read only.
> +
> What: /sys/class/scsi_device/*/device/hpb_param_sysfs/activation_thld
> Date: February 2021
> Contact: Avri Altman <avri.altman@wdc.com>
> diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
> index 0a088b47d5570..4149cdf19de92 100644
> --- a/drivers/ufs/core/ufs-sysfs.c
> +++ b/drivers/ufs/core/ufs-sysfs.c
> @@ -279,6 +279,42 @@ static const struct attribute_group ufs_sysfs_default_group = {
> .attrs = ufs_sysfs_ufshcd_attrs,
> };
>
> +static ssize_t clock_scaling_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct ufs_hba *hba = dev_get_drvdata(dev);
> +
> + return sysfs_emit(buf, "%d\n", ufshcd_is_clkscaling_supported(hba));
> +}
> +
> +static ssize_t write_booster_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct ufs_hba *hba = dev_get_drvdata(dev);
> +
> + return sysfs_emit(buf, "%d\n", ufshcd_is_wb_allowed(hba));
> +}
> +
> +static DEVICE_ATTR_RO(clock_scaling);
> +static DEVICE_ATTR_RO(write_booster);
> +
> +/*
> + * The "capabilities" sysfs group represents the effective capabilities of the
> + * host-device pair, i.e. the capabilities which are enabled in the driver for
> + * the specific host controller, supported by the host controller and are
> + * supported and/or have compatible configuration on the device side.

Why is this information not also in the Documentation/ABI/ entries as
well?

thanks,

greg k-h