On Tue, Aug 10, 2021 at 02:49:39PM +0900, 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>
> Reviewed-by: Hannes Reinecke <hare@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,
Hello Damien,
I do not fully understand if NCQ is only supported for AHCI controllers,
or if vanilla SATA controllers (without AHCI) can support it as well
(since NCQ is part of the ATA Command Set - 5).
However, I do think that you might have missed adding the
dev_attr_ncq_prio_supported
attribute for the ata_ncq_sdev_attrs struct in libata-sata.c
(The ata_ncq_sdev_attrs struct already has the dev_attr_ncq_prio_enable
attribute, so it makes sense that it should have the new supported
attribute as well.)
Kind regards,
Niklas
> &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;
