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ata: libata-sata: Improve link_power_management_supported sysfs attribute

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The link_power_management_supported sysfs attribute is currently set as
true even for ata ports that lack a .set_lpm() callback, e.g. dummy ports.

This is a bit silly, because while writing to the
link_power_management_policy sysfs attribute will make ata_scsi_lpm_store()
update ap->target_lpm_policy (thus sysfs will reflect the new value) and
call ata_port_schedule_eh() for the port, it is essentially a no-op.

This is because for a port without a .set_lpm() callback, once EH gets to
run, the ata_eh_link_set_lpm() will simply return, since the port does not
provide a .set_lpm() callback.

Thus, make sure that the link_power_management_supported sysfs attribute
is set to false for ports that lack a .set_lpm() callback. This way the
link_power_management_policy sysfs attribute will no longer be writable,
so we will no longer be misleading users to think that their sysfs write
actually does something.

Fixes: 0060beec0b ("ata: libata-sata: Add link_power_management_supported sysfs attribute")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Tested-by: Wolf <wolf@yoxt.cc>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
This commit is contained in:
Niklas Cassel 2026-01-12 13:20:48 +01:00 • committed by Damien Le Moal
parent 8f3fb33f8f
commit ce83767ea3
1 changed files with 1 additions and 1 deletions
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2
drivers/ata/libata-sata.c
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@ -909,7 +909,7 @@ 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)
if ((ap->flags & ATA_FLAG_NO_LPM) || !ap->ops->set_lpm)
return false;
ata_for_each_link(link, ap, EDGE) {