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SubjectRe: 2.6.25-rc6: CONFIG_USB_PERSIST forced on
Date
Am Montag 09 Juni 2008 23:56:51 schrieb Pavel Machek:
> On Mon 2008-06-09 14:39:10, Linus Torvalds wrote:
> >
> >
> > On Mon, 9 Jun 2008, Pavel Machek wrote:
> > >
> > > I believe we should just revert the "CONFIG_USB_PERSIST force on"
> > > patch, and solve this properly in 2.6.27.
> >
> > Why?
> >
> > The code would _still_ be buggy with that revert in place. You have to
> > enable CONFIG_USB_PERSIST just to get even the _possibility_ of the sane
> > behavior.
> >
> > If there is a problem with usblp, it just needs to be fixed.
>
> With USB_PERSIST on, you have problem on all drivers but usb-storage,
> AFAICT... because usb-storage seems to be the only driver implementing
> reset_resume.
>
> I guess it is possible to do something like "if reset_resume() is
> unavailable, try plain resume()" in usb/driver.c, but I'd really
> changes to the suspend/resume callback to go in -rc1 so that they are
> tested properly, and not hot-patch it now.

If a hotfix it must be, here's my take. It works for me, but it isn't
tested well.
Alan, what do you think?

Regards
Oliver

Signed-off-by: Oliver Neukum <oneukum@suse.de>

---

--- linux-2.6.25/drivers/usb/core/hub.c 2008-06-09 15:15:13.105058000 +0200
+++ alt/drivers/usb/core/hub.c 2008-06-09 15:43:29.964503000 +0200
@@ -648,7 +648,9 @@ static void hub_stop(struct usb_hub *hub
static void hub_restart(struct usb_hub *hub, int type)
{
struct usb_device *hdev = hub->hdev;
- int port1;
+ struct usb_interface *intf;
+ struct usb_driver *driver;
+ int port1, i;

/* Check each of the children to see if they require
* USB-PERSIST handling or disconnection. Also check
@@ -692,6 +694,14 @@ static void hub_restart(struct usb_hub *
*/
if (udev->persist_enabled && status == 0 &&
!(portstatus & USB_PORT_STAT_ENABLE)) {
+
+ /* check for devices not supporting reset_resume */
+ for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
+ intf = udev->actconfig->interface[i];
+ driver = to_usb_driver(intf->dev.driver);
+ if (!driver || !driver->reset_resume)
+ goto skip_reset_resume;
+ }
if (portchange & USB_PORT_STAT_C_ENABLE)
clear_port_feature(hub->hdev, port1,
USB_PORT_FEAT_C_ENABLE);
@@ -705,8 +715,11 @@ static void hub_restart(struct usb_hub *
* but as we may not lock the child device here
* we have to do a "logical" disconnect.
*/
- else if (type == HUB_RESET_RESUME)
- hub_port_logical_disconnect(hub, port1);
+ else {
+skip_reset_resume:
+ if (type == HUB_RESET_RESUME)
+ hub_port_logical_disconnect(hub, port1);
+ }
}

hub_activate(hub);

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