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SubjectRe: 2.6.25-rc6: CONFIG_USB_PERSIST forced on


On Tue, 10 Jun 2008, Oliver Neukum wrote:
>
> 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?

Hmm. I hate making functions more complex. Especially if it's an area
where we'd expect it to change in the future (ie I think we should aim for
taking into account whether a device is actually open or not). So here's a
cleaned-up alternative of your approach with the whole "is it persistent"
logic separated out into a function of its own.

Then, some day, if we get back-pointers to open devices, or we get drievr
hooks to say "am I mounted" or something, we have a logical place to do
those things.

Is there perhaps already a way to know whether a driver is actually
*active* or not (ie not just registered, but somebody has then opened it)?
I guess there isn't. Oh, well.

Linus

---
drivers/usb/core/hub.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 8eb4da3..3b0b58e 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -644,6 +644,46 @@ static void hub_stop(struct usb_hub *hub)

#ifdef CONFIG_PM

+static int persistent_device(struct usb_device *udev)
+{
+ int i, retval;
+ struct usb_host_config *actconfig;
+
+ /* Explicitly not marked persistent? */
+ if (!udev->persist_enabled)
+ return 0;
+
+ /* No active config? */
+ actconfig = udev->actconfig;
+ if (!actconfig)
+ return 0;
+
+ /* FIXME! We should check whether it's open here or not! */
+
+ /*
+ * Check that all drivers on the active interface have a
+ * 'reset_resume' entrypoint
+ */
+ retval = 0;
+ for (i = 0; i < actconfig->desc.bNumInterfaces; i++) {
+ struct usb_interface *intf;
+ struct usb_driver *driver;
+
+ intf = actconfig->interface[i];
+ driver = to_usb_driver(intf->dev.driver);
+ if (!driver)
+ continue;
+ if (!driver->reset_resume)
+ return 0;
+ /*
+ * We have at least one driver, and that one
+ * supports 'reset_resume'
+ */
+ retval = 1;
+ }
+ return retval;
+}
+
static void hub_restart(struct usb_hub *hub, int type)
{
struct usb_device *hdev = hub->hdev;
@@ -689,8 +729,8 @@ static void hub_restart(struct usb_hub *hub, int type)
* turn off the various status changes to prevent
* khubd from disconnecting it later.
*/
- if (udev->persist_enabled && status == 0 &&
- !(portstatus & USB_PORT_STAT_ENABLE)) {
+ if (status == 0 && !(portstatus & USB_PORT_STAT_ENABLE) &&
+ persistent_device(udev)) {
if (portchange & USB_PORT_STAT_C_ENABLE)
clear_port_feature(hub->hdev, port1,
USB_PORT_FEAT_C_ENABLE);

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