6.15-stable review patch. If anyone has any objections, please let me know.
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From: Damien Le Moal dlemoal@kernel.org
commit 0060beec0bfa647c4b510df188b1c4673a197839 upstream.
A port link power management (LPM) policy can be controlled using the link_power_management_policy sysfs host attribute. However, this attribute exists also for hosts that do not support LPM and in such case, attempting to change the LPM policy for the host (port) will fail with -EOPNOTSUPP.
Introduce the new sysfs link_power_management_supported host attribute to indicate to the user if a the port and the devices connected to the port for the host support LPM, which implies that the link_power_management_policy attribute can be used.
Since checking that a port and its devices support LPM is common between the new ata_scsi_lpm_supported_show() function and the existing ata_scsi_lpm_store() function, the new helper ata_scsi_lpm_supported() is introduced.
Fixes: 413e800cadbf ("ata: libata-sata: Disallow changing LPM state if not supported") Reported-by: Borah, Chaitanya Kumar chaitanya.kumar.borah@intel.com Reported-by: kernel test robot oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202507251014.a5becc3b-lkp@intel.com Signed-off-by: Damien Le Moal dlemoal@kernel.org Reviewed-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/ata/ata_piix.c | 1 drivers/ata/libahci.c | 1 drivers/ata/libata-sata.c | 53 +++++++++++++++++++++++++++++++++++----------- include/linux/libata.h | 1 4 files changed, 44 insertions(+), 12 deletions(-)
--- a/drivers/ata/ata_piix.c +++ b/drivers/ata/ata_piix.c @@ -1089,6 +1089,7 @@ static struct ata_port_operations ich_pa };
static struct attribute *piix_sidpr_shost_attrs[] = { + &dev_attr_link_power_management_supported.attr, &dev_attr_link_power_management_policy.attr, NULL }; --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -111,6 +111,7 @@ static DEVICE_ATTR(em_buffer, S_IWUSR | static DEVICE_ATTR(em_message_supported, S_IRUGO, ahci_show_em_supported, NULL);
static struct attribute *ahci_shost_attrs[] = { + &dev_attr_link_power_management_supported.attr, &dev_attr_link_power_management_policy.attr, &dev_attr_em_message_type.attr, &dev_attr_em_message.attr, --- a/drivers/ata/libata-sata.c +++ b/drivers/ata/libata-sata.c @@ -900,14 +900,52 @@ static const char *ata_lpm_policy_names[ [ATA_LPM_MIN_POWER] = "min_power", };
+/* + * Check if a port supports link power management. + * Must be called with the port locked. + */ +static bool ata_scsi_lpm_supported(struct ata_port *ap) +{ + struct ata_link *link; + struct ata_device *dev; + + if (ap->flags & ATA_FLAG_NO_LPM) + return false; + + ata_for_each_link(link, ap, EDGE) { + ata_for_each_dev(dev, &ap->link, ENABLED) { + if (dev->quirks & ATA_QUIRK_NOLPM) + return false; + } + } + + return true; +} + +static ssize_t ata_scsi_lpm_supported_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct Scsi_Host *shost = class_to_shost(dev); + struct ata_port *ap = ata_shost_to_port(shost); + unsigned long flags; + bool supported; + + spin_lock_irqsave(ap->lock, flags); + supported = ata_scsi_lpm_supported(ap); + spin_unlock_irqrestore(ap->lock, flags); + + return sysfs_emit(buf, "%d\n", supported); +} +DEVICE_ATTR(link_power_management_supported, S_IRUGO, + ata_scsi_lpm_supported_show, NULL); +EXPORT_SYMBOL_GPL(dev_attr_link_power_management_supported); + static ssize_t ata_scsi_lpm_store(struct device *device, struct device_attribute *attr, const char *buf, size_t count) { struct Scsi_Host *shost = class_to_shost(device); struct ata_port *ap = ata_shost_to_port(shost); - struct ata_link *link; - struct ata_device *dev; enum ata_lpm_policy policy; unsigned long flags;
@@ -924,20 +962,11 @@ static ssize_t ata_scsi_lpm_store(struct
spin_lock_irqsave(ap->lock, flags);
- if (ap->flags & ATA_FLAG_NO_LPM) { + if (!ata_scsi_lpm_supported(ap)) { count = -EOPNOTSUPP; goto out_unlock; }
- ata_for_each_link(link, ap, EDGE) { - ata_for_each_dev(dev, &ap->link, ENABLED) { - if (dev->quirks & ATA_QUIRK_NOLPM) { - count = -EOPNOTSUPP; - goto out_unlock; - } - } - } - ap->target_lpm_policy = policy; ata_port_schedule_eh(ap); out_unlock: --- a/include/linux/libata.h +++ b/include/linux/libata.h @@ -545,6 +545,7 @@ typedef void (*ata_postreset_fn_t)(struc
extern struct device_attribute dev_attr_unload_heads; #ifdef CONFIG_SATA_HOST +extern struct device_attribute dev_attr_link_power_management_supported; 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;