Re: [PATCH v2 9/9] scsi: mpt3sas: Introduce sas_ncq_prio_supported sysfs sttribute

[Hannes Reinecke <hare@suse.de>]

On 8/6/21 9:42 AM, Damien Le Moal wrote:
> Similarly to AHCI, introduce the device sysfs attribute
> sas_ncq_prio_supported to advertize if a SATA device supports the NCQ
> priority feature. Without this new attribute, the user can only
> discover if a SATA device supports NCQ priority by trying to enable
> the feature use with the sas_ncq_prio_enable sysfs device attribute,
> which fails when the device does not support high priroity commands.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> ---
>  drivers/scsi/mpt3sas/mpt3sas_ctl.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/scsi/mpt3sas/mpt3sas_ctl.c b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
> index b66140e4c370..f83d4d32d459 100644
> --- a/drivers/scsi/mpt3sas/mpt3sas_ctl.c
> +++ b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
> @@ -3918,6 +3918,24 @@ sas_device_handle_show(struct device *dev, struct device_attribute *attr,
>  }
>  static DEVICE_ATTR_RO(sas_device_handle);
>  
> +/**
> + * sas_ncq_prio_supported_show - Indicate if device supports NCQ priority
> + * @dev: pointer to embedded device
> + * @attr: sas_ncq_prio_supported attribute descriptor
> + * @buf: the buffer returned
> + *
> + * A sysfs 'read-only' sdev attribute, only works with SATA
> + */
> +static ssize_t
> +sas_ncq_prio_supported_show(struct device *dev,
> +			    struct device_attribute *attr, char *buf)
> +{
> +	struct scsi_device *sdev = to_scsi_device(dev);
> +
> +	return sysfs_emit(buf, "%d\n", scsih_ncq_prio_supp(sdev));
> +}
> +static DEVICE_ATTR_RO(sas_ncq_prio_supported);
> +
>  /**
>   * sas_ncq_prio_enable_show - send prioritized io commands to device
>   * @dev: pointer to embedded device
> @@ -3960,6 +3978,7 @@ static DEVICE_ATTR_RW(sas_ncq_prio_enable);
>  struct device_attribute *mpt3sas_dev_attrs[] = {
>  	&dev_attr_sas_address,
>  	&dev_attr_sas_device_handle,
> +	&dev_attr_sas_ncq_prio_supported,
>  	&dev_attr_sas_ncq_prio_enable,
>  	NULL,
>  };
> 
One wonders where the relationship to the previous patches are, but hey:

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
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