@@ -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
};
@@ -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 : snprintf(buf, 20, "%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)
@@ -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;
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@wdc.com> --- drivers/ata/libahci.c | 1 + drivers/ata/libata-sata.c | 24 ++++++++++++++++++++++++ include/linux/libata.h | 1 + 3 files changed, 26 insertions(+)