Hi, I'm having some problems with the link_power_management_policy on my Dell XPS13 9333. Changing policy from min_power or medium_power to max_performance causes the following errors: [ 3955.667086] ahci 0000:00:1f.2: port does not support device sleep [ 3958.257106] ata3.00: exception Emask 0x10 SAct 0x40 SErr 0x50000 action 0xe frozen [ 3958.257110] ata3.00: irq_stat 0x00400000, PHY RDY changed [ 3958.257113] ata3: SError: { PHYRdyChg CommWake } [ 3958.257116] ata3.00: failed command: READ FPDMA QUEUED [ 3958.257120] ata3.00: cmd 60/00:30:c8:60:10/01:00:1d:00:00/40 tag 6 ncq 131072 in res 40/00:34:c8:60:10/00:00:1d:00:00/40 Emask 0x10 (ATA bus error) [ 3958.257122] ata3.00: status: { DRDY } [ 3958.257126] ata3: hard resetting link [ 3958.981727] ata3: SATA link up 6.0 Gbps (SStatus 133 SControl 300) [ 3958.984994] ata3.00: configured for UDMA/133 [ 3958.997686] ahci 0000:00:1f.2: port does not support device sleep [ 3958.997698] ata3: EH complete Sometimes I get "failed command: WRITE FPDMA QUEUED" multiple times. As far as I know, this had always happened and it was confirmed by another user. I've also come across some logs of the same system and saw the same errors here and there, so it shouldn't be a problem of my laptop in particular. What I find interesting is that transitions from min_power to medium_power and vice versa do not cause these errors. There are only problem switching from min_power and medium_power to max_performance. Doing the opposite, i.e. from max_performance to min_power or medium_power, seems to work fine. As a consequence of these continuous errors, the speed is reduced from 6.0 Gbps to 1.5 Gbps. I'd prefer not to disable LPM as it saves a considerable amount of power when I'm using the battery. For this reason I'm currently using medium_power and min_power only to prevent errors. Is it normal that these errors appears only when I switch to max_performance? Was something similar observed on other systems? Thanks, Gabriele -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html