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    Subject[PATCH] SATA / AHCI: Do not play with the link PM during suspend to RAM (was: Re: HDD not suspending properly / dead on resume)
    On Saturday, July 10, 2010, Tejun Heo wrote:
    > On 07/10/2010 08:50 AM, Stephan Diestelhorst wrote:
    > >> I have a box where this problem is kind of reproducible, but it happens _very_
    > >> rarely. Also I can't reproduce it on demand running suspend-resume in a tight
    > >> loop. Are you able to reproduce it more regurarly?
    > >
    > > For me it is much more reproducible. If I run multiple direct writing
    > > dd-s to the disk in question I trigger it rather reliably (~75% or
    > > higher). See the attached script from an earlier email.
    > > Maybe that helps triggering your case more reliabl, too?
    > Can you please try the following git tree?
    > git:// libata-irq-expect

    That didn't help, but the appended patch fixes the problem for me.


    From: Rafael J. Wysocki <>
    Subject: SATA / AHCI: Do not play with the link PM during suspend to RAM

    My Acer Ferrari One occasionally loses communication with the disk
    (which in fact is an Intel SSD) during suspend to RAM. The symptom
    is that the IDENTIFY command times out during suspend and the device
    is dropped by the kernel, so it is not available during resume and
    the system is unuseable as a result. The failure is not readily
    reproducible, although it happens once every several suspends and
    it always happens after the disk has been shut down by the SCSI
    layer's suspend routine.

    I was able to track this issue down to the link PM manipulations
    carried out by ata_host_suspend(), which probably means that the
    SSD's firmware is not implemented correctly. However, the AHCI
    driver, which is used on the affected box, doesn't really need to do
    anything with the link PM during suspend to RAM, because the whole
    controller is going to be put into D3 by ata_pci_device_do_suspend()
    immediately and it will undergo full reset during the subsequent
    resume anyway. For this reason, make the AHCI driver avoid calling
    ata_host_suspend() during suspend to RAM which fixes the problem and
    makes sense as a general optimization.

    Signed-off-by: Rafael J. Wysocki <>
    drivers/ata/ahci.c | 11 ++++++++++-
    1 file changed, 10 insertions(+), 1 deletion(-)

    Index: linux-2.6/drivers/ata/ahci.c
    --- linux-2.6.orig/drivers/ata/ahci.c
    +++ linux-2.6/drivers/ata/ahci.c
    @@ -595,6 +595,7 @@ static int ahci_pci_device_suspend(struc
    struct ahci_host_priv *hpriv = host->private_data;
    void __iomem *mmio = hpriv->mmio;
    u32 ctl;
    + int rc = 0;

    if (mesg.event & PM_EVENT_SUSPEND &&
    hpriv->flags & AHCI_HFLAG_NO_SUSPEND) {
    @@ -614,7 +615,15 @@ static int ahci_pci_device_suspend(struc
    readl(mmio + HOST_CTL); /* flush */

    - return ata_pci_device_suspend(pdev, mesg);
    + if (mesg.event == PM_EVENT_SUSPEND)
    + pdev->dev.power.power_state = mesg;
    + else
    + rc = ata_host_suspend(host, mesg);
    + if (!rc)
    + ata_pci_device_do_suspend(pdev, mesg);
    + return rc;

    static int ahci_pci_device_resume(struct pci_dev *pdev)

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      Last update: 2010-07-28 23:55    [W:0.023 / U:75.992 seconds]
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