On 7/29/25 01:24, Borah, Chaitanya Kumar wrote: > > > On 7/28/2025 9:41 AM, Damien Le Moal wrote: >> On 7/25/25 3:43 PM, Borah, Chaitanya Kumar wrote: >>> For some context in our kms_pm_rpm tests, we enable min_power policy for >>> SATA >>> so that we can reach deep runtime power states and restore the original >>> policy >>> after finishing. [5][6] >>> >>> IIUC, the above change is based on spec and not something which can be >>> reverted. So as I see it, we have to drop this code path for external ports. >>> However I am not sure if we can achieve deep power states without enforcing >>> it >>> through the sysfs entry. >>> >>> Atleast for the basic-rte subtest, the test passes if we comment out the >>> functions controlling the SATA ports. We will need more testing to >>> determine if >>> this approach work. Any thoughts on it? >>> >>> Also, are there other ways to detect a port is external other than receiving >>> EOPNOTSUPP on the sysfs write? >> >> The attached patch adds the "link_power_management_supported" sysfs device >> attribute for drives connected to AHCI. Would that work for you ? >> > > Yes this could work. I quickly hacked the test to ignore writing policy > if this file returns 0. > > Here is the state of the machine I am testing on. > > /sys/class/scsi_host/host0/link_power_management_supported: 0 > /sys/class/scsi_host/host1/link_power_management_supported: 0 > /sys/class/scsi_host/host2/link_power_management_supported: 0 > /sys/class/scsi_host/host3/link_power_management_supported: 0 > /sys/class/scsi_host/host4/link_power_management_supported: 1 > /sys/class/scsi_host/host5/link_power_management_supported: 1 > /sys/class/scsi_host/host6/link_power_management_supported: 1 > /sys/class/scsi_host/host7/link_power_management_supported: 1
Looks good. My test machine looks exactly like this too. I will send out this patch as it is useful anyway regardless of external/hotplug ports since not all adapters/drives support LPM. When posting this, can I tag it as a solution to the regression ? And in addition to this patch, I will work on a flexible way of ignoring hotplug. -- Damien Le Moal Western Digital Research
