diff options
author | Alan Stern <stern@rowland.harvard.edu> | 2009-02-26 16:21:02 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-03-25 00:20:38 +0100 |
commit | 4fe0387afa893b44c5a21b9bfbb0888354ef4656 (patch) | |
tree | b86045c34fab6ff5146dd3ca6be70d54514a1359 /drivers/usb/core | |
parent | USB: remove phidget drivers from kernel tree. (diff) | |
download | linux-4fe0387afa893b44c5a21b9bfbb0888354ef4656.tar.xz linux-4fe0387afa893b44c5a21b9bfbb0888354ef4656.zip |
USB: don't send Set-Interface after reset
This patch (as1221) changes the way usbcore reinitializes a device
following a reset or a reset-resume. Currently we call
usb_set_interface() for every interface in the active configuration;
this is to put the interface into the same altsetting as before the
reset and to make sure that the host's endpoint state matches the
device's endpoint state.
However, sending a Set-Interface request is a waste of time if an
interface was already in altsetting 0 before the reset, since it is
certainly in altsetting 0 afterward. In addition, many devices can't
handle Set-Interface requests -- they crash when they receive them.
So instead, the patch adds code to check each interface. If the
interface wasn't in altsetting 0 before the reset, we go head with the
Set-Interface request as before. But if it was then we skip sending
the Set-Interface request, and we clear out the host-side endpoint
state by calling usb_disable_interface() followed by
usb_enable_interface().
The patch also adds a couple of new comments to explain what's going
on.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/core')
-rw-r--r-- | drivers/usb/core/hub.c | 23 |
1 files changed, 16 insertions, 7 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index f17d9ebc44af..81eb3e6b6592 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -3393,10 +3393,10 @@ static int usb_reset_and_verify_device(struct usb_device *udev) udev->descriptor = descriptor; /* for disconnect() calls */ goto re_enumerate; } - + + /* Restore the device's previous configuration */ if (!udev->actconfig) goto done; - ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0), USB_REQ_SET_CONFIGURATION, 0, udev->actconfig->desc.bConfigurationValue, 0, @@ -3409,16 +3409,25 @@ static int usb_reset_and_verify_device(struct usb_device *udev) } usb_set_device_state(udev, USB_STATE_CONFIGURED); + /* Put interfaces back into the same altsettings as before. + * Don't bother to send the Set-Interface request for interfaces + * that were already in altsetting 0; besides being unnecessary, + * many devices can't handle it. Instead just reset the host-side + * endpoint state. + */ for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) { struct usb_interface *intf = udev->actconfig->interface[i]; struct usb_interface_descriptor *desc; - /* set_interface resets host side toggle even - * for altsetting zero. the interface may have no driver. - */ desc = &intf->cur_altsetting->desc; - ret = usb_set_interface(udev, desc->bInterfaceNumber, - desc->bAlternateSetting); + if (desc->bAlternateSetting == 0) { + usb_disable_interface(udev, intf, true); + usb_enable_interface(udev, intf, true); + ret = 0; + } else { + ret = usb_set_interface(udev, desc->bInterfaceNumber, + desc->bAlternateSetting); + } if (ret < 0) { dev_err(&udev->dev, "failed to restore interface %d " "altsetting %d (error=%d)\n", |