Re: [PATCH] usb: Fix out of sync data toggle if a configured device is reconfigured

[Felipe Balbi <balbi@kernel.org>]

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Hi,

Mathias Nyman <mathias.nyman@linux.intel.com> writes:
> Userspace drivers that use a SetConfiguration() request to "lightweight"
> reset a already configured usb device might cause data toggles to get out
        ^
        an

> of sync between the device and host, and the device becomes unusable.
>
> The xHCI host requires endpoints to be dropped and added back to reset the
> toggle. USB core avoids these otherwise extra steps if the current active
> configuration is the same as the new requested configuration.
>
> A SetConfiguration() request will reset the device side data toggles.
> Make sure usb core drops and adds back the endpoints in this case.
>
> To avoid code duplication split the current usb_disable_device() function
> and reuse the endpoint specific part.

it looks like the refactoring is unrelated to the bug fix, perhaps? But
then again, it would mean adding more duplication just for the sake of
keeping bug fixes as pure bug fixes. No strong opinion.

> Cc: stable <stable@vger.kernel.org>

missing fixes?

> Tested-by: Martin Thierer <mthierer@gmail.com>
> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
> ---
>  drivers/usb/core/message.c | 92 ++++++++++++++++++--------------------
>  1 file changed, 43 insertions(+), 49 deletions(-)
>
> diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
> index 6197938dcc2d..a1f67efc261f 100644
> --- a/drivers/usb/core/message.c
> +++ b/drivers/usb/core/message.c
> @@ -1205,6 +1205,35 @@ void usb_disable_interface(struct usb_device *dev, struct usb_interface *intf,
>  	}
>  }
>  
> +/*
> + * usb_disable_device_endpoints -- Disable all endpoints for a device
> + * @dev: the device whose endpoints are being disabled
> + * @skip_ep0: 0 to disable endpoint 0, 1 to skip it.
> + */
> +static void usb_disable_device_endpoints(struct usb_device *dev, int skip_ep0)
> +{
> +	struct usb_hcd *hcd = bus_to_hcd(dev->bus);
> +	int i;
> +
> +	if (hcd->driver->check_bandwidth) {
> +

maybe remove this blank line?

> +		/* First pass: Cancel URBs, leave endpoint pointers intact. */
> +		for (i = skip_ep0; i < 16; ++i) {
> +			usb_disable_endpoint(dev, i, false);
> +			usb_disable_endpoint(dev, i + USB_DIR_IN, false);
> +		}

maybe a blank line here?

> +		/* Remove endpoints from the host controller internal state */
> +		mutex_lock(hcd->bandwidth_mutex);
> +		usb_hcd_alloc_bandwidth(dev, NULL, NULL, NULL);
> +		mutex_unlock(hcd->bandwidth_mutex);
> +	}

maybe a blank line here?

> +	/* Second pass: remove endpoint pointers */
> +	for (i = skip_ep0; i < 16; ++i) {
> +		usb_disable_endpoint(dev, i, true);
> +		usb_disable_endpoint(dev, i + USB_DIR_IN, true);
> +	}
> +}
> +
>  /**
>   * usb_disable_device - Disable all the endpoints for a USB device
>   * @dev: the device whose endpoints are being disabled
> @@ -1522,6 +1536,9 @@ EXPORT_SYMBOL_GPL(usb_set_interface);
>   * The caller must own the device lock.
>   *
>   * Return: Zero on success, else a negative error code.
> + *
> + * If this routine fails the device will probably be in an unusable state
> + * with endpoints disabled, and interfaces only partially enabled.

should you force U3 in that case?

-- 
balbi

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