On Mon, Apr 18, 2022 at 02:00:45PM -0700, Evan Green wrote:
> The PM_EVENT_FREEZE and PM_EVENT_QUIESCE messages should cause the
> device to stop generating interrupts. USB core was previously allowing
> devices that were already runtime suspended to keep remote wakeup
> enabled if they had gone down that way. This violates the contract with
> pm, and can potentially cause MSI interrupts to be lost.
>
> Change that so that if a device is runtime suspended with remote wakeups
> enabled, it will be resumed to ensure remote wakeup is always disabled
> across a freeze.
>
> Signed-off-by: Evan Green <evgreen@xxxxxxxxxxxx>
> ---
>
> (no changes since v1)
>
> drivers/usb/core/driver.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> index 355ed33a21792b..93c8cf66adccec 100644
> --- a/drivers/usb/core/driver.c
> +++ b/drivers/usb/core/driver.c
> @@ -1533,20 +1533,18 @@ static void choose_wakeup(struct usb_device *udev, pm_message_t msg)
> {
> int w;
>
> - /* Remote wakeup is needed only when we actually go to sleep.
> - * For things like FREEZE and QUIESCE, if the device is already
> - * autosuspended then its current wakeup setting is okay.
> + /* For FREEZE/QUIESCE, disable remote wakeups so no interrupts get generated
> + * by the device.
You mean "by the host controller". USB devices don't generate
interrupts; they generate wakeup requests (which can cause a host
controller to generate an interrupt).
> */
> if (msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_QUIESCE) {
> - if (udev->state != USB_STATE_SUSPENDED)
> - udev->do_remote_wakeup = 0;
> - return;
> - }
> + w = 0;
>
> - /* Enable remote wakeup if it is allowed, even if no interface drivers
> - * actually want it.
> - */
> - w = device_may_wakeup(&udev->dev);
> + } else {
> + /* Enable remote wakeup if it is allowed, even if no interface drivers
> + * actually want it.
> + */
> + w = device_may_wakeup(&udev->dev);
> + }
>
> /* If the device is autosuspended with the wrong wakeup setting,
> * autoresume now so the setting can be changed.
> --
I would prefer it if you reformatted the comments to agree with the
current style:
/*
* Blah blah blah
*/
and to avoid line wrap beyond 80 columns. Apart from that:
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Alan Stern
