Hi, Alan,
Please see my comments:
2009/4/15 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>:
> On Wed, 15 Apr 2009, Eric Miao wrote:
>
>> From a0e1b72f073f4b3dd811b6c4fe4cae4044e56d45 Mon Sep 17 00:00:00 2001
>> From: Yong Yao <yaoyong@xxxxxxxxxxx>
>> Date: Wed, 15 Apr 2009 13:08:56 +0800
>> Subject: [PATCH] usb core: HNP support in hub.c
>>
>> When starting HNP, we need reset the port, so USB_PORT_STAT_ENABLE is
>> set. In such case, we should not disable the port, otherwise the port
>> will be disconnected. It will cause that HNP to fail, since the state
>> machine will change from OTG_STATE_B_HOST to OTG_STATE_B_PERIPHERAL
>> after the port is disconnected.
>>
>> Signed-off-by: Yong Yao <yaoyong@xxxxxxxxxxx>
>> Signed-off-by: Eric Miao <eric.miao@xxxxxxxxxxx>
>> ---
>>
>> Alan, this is a follow-up of the previous thread, with the fix
>> to be OTG specific, please help review.
>>
>> drivers/usb/core/hub.c | 7 +++++--
>> 1 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
>> index b19cbfc..2e28f48 100644
>> --- a/drivers/usb/core/hub.c
>> +++ b/drivers/usb/core/hub.c
>> @@ -688,8 +688,11 @@ static void hub_activate(struct usb_hub *hub,
>> enum hub_activation_type type)
>> * Unconnected ports should likewise be disabled (paranoia),
>> * and so should ports for which we have no usb_device.
>> */
>> - if ((portstatus & USB_PORT_STAT_ENABLE) && (
>> - type != HUB_RESUME ||
>> + if ((portstatus & USB_PORT_STAT_ENABLE) &&
>> +#ifdef CONFIG_USB_OTG
>> + !(hdev->bus->is_b_host) &&
>> +#endif
>> + (type != HUB_RESUME ||
>> !(portstatus & USB_PORT_STAT_CONNECTION) ||
>> !udev ||
>> udev->state == USB_STATE_NOTATTACHED)) {
>
> This is a lot better than the previous patch. I wonder if there is a
> simple way to eliminate the ugly preprocessor test. For instance, if
> CONFIG_USB_OTG isn't defined, won't hdev->bus->is_b_host always be 0?
>
[Yong] As I know, only OTG device will change the is_b_host. But I
think we may reserve this preprecessor in order to align with the
previous code.
> I also wonder if this is truly correct. Evidently you want the new
> behavior to apply during the HNP exchange, but what about at other
> times? Suppose the device is already a B-host when its root hub gets
> suspended; what would happen then?
[Yong] when root hub gets suspended, port will disconnect. In such
case, otg state machine will change from OTG_STATE_B_HOST to
OTG_STATE_B_PERIPHERAL. At that time, the B device will be back as the
peripheral. we don't use host port any more.
>
> Alan Stern
>
Regards
Yong
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
