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    SubjectPATCH (as112) Re: USB APM suspend
    On Sun, 21 Sep 2003, David Brownell wrote:

    > Alan Stern wrote:
    > > Here's a piece from my system log, when I did "apm --suspend". The
    > > usb_device_suspend/resume messages are things I added for debugging.
    > > Why was this routine called twice? (Don't be fooled by the timestamps; I
    > > think the "suspend D4 --> D3" message was created during the suspend but
    > > not read by syslogd until after the resume.)
    > That's happened for as long as I remember (2.4 also).
    > Still seems buglike to me, maybe 2.6 will finally squish it...

    Well, the code path is easy enough to find. If you look at suspend() in
    arch/i386/kernel/apm.c, you'll see calls to pm_send_all() and
    device_suspend(). They both end up filtering down to the USB HC drivers.
    The bad one is pm_send_all(); it comes too soon.

    By the way, David, apparently core/hcd-pci.c wants the HC drivers to set
    the hcd state to USB_STATE_SUSPENDED, but a simple grep shows that neither
    the EHCI nor the OHCI driver does so. That certainly looks like an
    oversight, though I'm not sure in which source file.

    Meanwhile, here's a simple patch to improve logging during suspend and
    resume. Greg, if David approves please apply it.

    Alan Stern

    ===== hcd-pci.c 1.35 vs edited =====
    --- 1.35/drivers/usb/core/hcd-pci.c Wed Sep 3 11:47:17 2003
    +++ edited/drivers/usb/core/hcd-pci.c Mon Sep 22 11:02:37 2003
    @@ -273,17 +273,17 @@
    int retval = 0;

    hcd = pci_get_drvdata(dev);
    + dev_dbg (hcd->controller, "suspend D%d --> D%d\n",
    + dev->current_state, state);
    switch (hcd->state) {
    case USB_STATE_HALT:
    dev_dbg (hcd->controller, "halted; hcd not suspended\n");
    - dev_dbg (hcd->controller, "suspend D%d --> D%d\n",
    - dev->current_state, state);
    + dev_dbg (hcd->controller, "hcd already suspended\n");
    - dev_dbg (hcd->controller, "suspend to state %d\n", state);
    /* remote wakeup needs hub->suspend() cooperation */
    // pci_enable_wake (dev, 3, 1);

    @@ -292,6 +292,9 @@
    /* driver may want to disable DMA etc */
    hcd->state = USB_STATE_QUIESCING;
    retval = hcd->driver->suspend (hcd, state);
    + if (retval)
    + dev_dbg (hcd->controller, "suspend fail, retval %d\n",
    + retval);

    pci_set_power_state (dev, state);
    @@ -311,6 +314,9 @@
    int retval;

    hcd = pci_get_drvdata(dev);
    + dev_dbg (hcd->controller, "resume from state D%d\n",
    + dev->current_state);
    if (hcd->state != USB_STATE_SUSPENDED) {
    dev_dbg (hcd->controller, "can't resume, not suspended!\n");
    return -EL3HLT;
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      Last update: 2005-03-22 13:48    [W:0.025 / U:16.504 seconds]
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