From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: SATA link power management issues Date: Fri, 9 Jan 2015 17:00:18 -0500 Message-ID: <20150109220018.GH2785@htj.dyndns.org> References: <3352987.ugV1Ipy7Z5@xps13> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-qg0-f46.google.com ([209.85.192.46]:37541 "EHLO mail-qg0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751217AbbAIWAV (ORCPT ); Fri, 9 Jan 2015 17:00:21 -0500 Content-Disposition: inline In-Reply-To: <3352987.ugV1Ipy7Z5@xps13> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Gabriele Mazzotta Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org Hello, Gabriele. On Thu, Jan 08, 2015 at 08:37:35PM +0100, Gabriele Mazzotta wrote: > 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 Ah, it actually happens. > [ 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. Always? Or does it sometimes get lucky and stabilize at a higher speed? > 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? It's not normal. It definitely doesn't happen with all devices. I guess it could be a quirk from the device side. What's on the other side of the connector? Can you post the full kernel log after such incidence? Thanks. -- tejun