On 8/6/21 1:11 PM, Damien Le Moal wrote:
> Currently, the only way a user can determine if a SATA device supports
> NCQ priority is to try to enable the use of this feature using the
> ncq_prio_enable sysfs device attribute. If enabling the feature fails,
> it is because the device does not support NCQ priority. Otherwise, the
> feature is enabled and indicates that the device supports NCQ priority.
>
> Improve this odd interface by introducing the read-only
> ncq_prio_supported sysfs device attribute to indicate if a SATA device
> supports NCQ priority. The value of this attribute reflects if the
> device flag ATA_DFLAG_NCQ_PRIO is set or cleared.
>
> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
> ---
> drivers/ata/libahci.c | 1 +
> drivers/ata/libata-sata.c | 24 ++++++++++++++++++++++++
> include/linux/libata.h | 1 +
> 3 files changed, 26 insertions(+)
>
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index fec2e9754aed..5b3fa2cbe722 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -125,6 +125,7 @@ EXPORT_SYMBOL_GPL(ahci_shost_attrs);
> struct device_attribute *ahci_sdev_attrs[] = {
> &dev_attr_sw_activity,
> &dev_attr_unload_heads,
> + &dev_attr_ncq_prio_supported,
> &dev_attr_ncq_prio_enable,
> NULL
> };
> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
> index dc397ebda089..5566fd4bb38f 100644
> --- a/drivers/ata/libata-sata.c
> +++ b/drivers/ata/libata-sata.c
> @@ -834,6 +834,30 @@ DEVICE_ATTR(link_power_management_policy, S_IRUGO | S_IWUSR,
> ata_scsi_lpm_show, ata_scsi_lpm_store);
> EXPORT_SYMBOL_GPL(dev_attr_link_power_management_policy);
>
> +static ssize_t ata_ncq_prio_supported_show(struct device *device,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct scsi_device *sdev = to_scsi_device(device);
> + struct ata_port *ap = ata_shost_to_port(sdev->host);
> + struct ata_device *dev;
> + bool ncq_prio_supported;
> + int rc = 0;
> +
> + spin_lock_irq(ap->lock);
> + dev = ata_scsi_find_dev(ap, sdev);
> + if (!dev)
> + rc = -ENODEV;
> + else
> + ncq_prio_supported = dev->flags & ATA_DFLAG_NCQ_PRIO;
> + spin_unlock_irq(ap->lock);
> +
> + return rc ? rc : sysfs_emit(buf, "%u\n", ncq_prio_supported);
> +}
> +
> +DEVICE_ATTR(ncq_prio_supported, S_IRUGO, ata_ncq_prio_supported_show, NULL);
> +EXPORT_SYMBOL_GPL(dev_attr_ncq_prio_supported);
> +
> static ssize_t ata_ncq_prio_enable_show(struct device *device,
> struct device_attribute *attr,
> char *buf)
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index b23f28cfc8e0..a2d1bae7900b 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -539,6 +539,7 @@ typedef void (*ata_postreset_fn_t)(struct ata_link *link, unsigned int *classes)
> extern struct device_attribute dev_attr_unload_heads;
> #ifdef CONFIG_SATA_HOST
> extern struct device_attribute dev_attr_link_power_management_policy;
> +extern struct device_attribute dev_attr_ncq_prio_supported;
> extern struct device_attribute dev_attr_ncq_prio_enable;
> extern struct device_attribute dev_attr_em_message_type;
> extern struct device_attribute dev_attr_em_message;
>
Alternative would have been to make the 'ncq_prio_enable' attribute
visible only when NCQ prio is supported, but not sure if that works out.
So:
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
