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Date: Thu, 16 Dec 2010 10:10:16 +0200
From: Felipe Balbi <balbi@ti.com>
Subject: Re: [RFC 2/5] USB: core: OTG Supplement Revision 2.0 updates
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 <Pine.LNX.4.44L0.1012151638260.2171-100000@iolanthe.rowland.org>
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To: Alan Stern <stern@rowland.harvard.edu>
Cc: Felipe Balbi <balbi@ti.com>, Pavankumar Kondeti <pkondeti@codeaurora.org>, linux-usb@vger.kernel.org, linux-arm-msm@vger.kernel.org

On Wed, Dec 15, 2010 at 04:39:13PM -0500, Alan Stern wrote:
>On Wed, 15 Dec 2010, Felipe Balbi wrote:
>
>> >+{
>> >+	int ret;
>> >+	struct usb_bus *bus =
>> >+		container_of(work, struct usb_bus, hnp_polling.work);
>> >+	struct usb_device *udev = bus->root_hub->children[bus->otg_port - 1];
>> >+	u8 *status = kmalloc(sizeof(*status), GFP_KERNEL);
>>
>> how about:
>>
>> u8 status;
>>
>> and...
>>
>> >+	if (!status)
>> >+		return;
>> >+
>> >+	ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
>> >+		USB_REQ_GET_STATUS, USB_DIR_IN | USB_RECIP_DEVICE,
>> >+		0, OTG_STATUS_SELECTOR, status, sizeof(*status),
>>
>> 0, OTG_STATUS_SELECTOR, &status, sizeof(status);
>> ??
>
>You mustn't do DMA to addresses on the stack.

oh, ok. Forgot other controllers will do DMA for control message too.
MUSB won't.

-- 
balbi