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Commit fdef8b4d authored Oct 13, 2013 by Ido Shayevitz

usb: gadget: ci13xxx: ensure exit from lpm on software connect/disconnect



In case the USB gadget controller is in low power mode (lpm) due
to bus suspend, the controller may not be accessible, however
the gadget framework still allow software disconnect and connect using the
pullup operation. This may results with a crash when we try to access
the controller.

Therefore we must resume the controller and exit lpm before do any
write/read operations to the controller registers.
Write helper function to accomplish that and use it upon pullup operation.

CRs-Fixed: 550217
Change-Id: I0969cfe39843e50c040abaf5648105a345456e64
Signed-off-by: Ido Shayevitz <idos@codeaurora.org>

parent 66d0b021

drivers/usb/gadget/ci13xxx_udc.c

+69 −0

Original line number	Diff line number	Diff line
		@@ -2964,6 +2964,66 @@ delegate:
		}
		}

		/**
		* ci13xxx_exit_lpm: Exit controller from low power mode
		* @udc: UDC descriptor
		* @allow_sleep: Are we in preemptible context or not.
		*
		* This function check if controller is in low power mode and if so, exit from
		* the low power mode.
		*
		* In case the controller is in low power mode, registers are not accessible,
		* therefore this function can be used as utility function to ensure exit from
		* low power mode before do registers read/write operations.
		*
		* Return 0 if not in low power mode and read/write operations are safe.
		* Return -EAGAIN in case exit from low power mode was initiated, but it is not
		* safe yet to use read/write operations against the controller registers.
		*/
		static int ci13xxx_exit_lpm(struct ci13xxx *udc, bool allow_sleep)
		{
		if (!udc)
		return -ENODEV;

		/* Check if the controller is in low power mode state */
		if (udc->udc_driver->in_lpm &&
		udc->udc_driver->in_lpm(udc) &&
		udc->transceiver) {

		dev_dbg(udc->transceiver->dev,
		"%s: Exit from low power mode\n",
		__func__);

		/*
		* Resume of the controller may be done
		* asynchronically in deffered context.
		*/
		usb_phy_set_suspend(udc->transceiver, 0);

		/*
		* Wait for controller resume to finish in case of non atomic
		* context or return EAGAIN otherwise.
		*/
		if (allow_sleep) {
		while (udc->udc_driver->in_lpm(udc))
		usleep(1);
		} else {
		/*
		* Return EAGAIN only in case controller resume
		* was done asynchronically.
		*/
		if (udc->udc_driver->in_lpm(udc)) {
		dev_err(udc->transceiver->dev,
		"%s: Unable to exit lpm\n",
		__func__);
		return -EAGAIN;
		}
		}
		}

		return 0;
		}

		/******************************************************************************
		* ENDPT block
		*****************************************************************************/
		@@ -3515,6 +3575,7 @@ static int ci13xxx_pullup(struct usb_gadget *_gadget, int is_active)
		{
		struct ci13xxx *udc = container_of(_gadget, struct ci13xxx, gadget);
		unsigned long flags;
		int ret;

		spin_lock_irqsave(udc->lock, flags);
		udc->softconnect = is_active;
		@@ -3525,6 +3586,14 @@ static int ci13xxx_pullup(struct usb_gadget *_gadget, int is_active)
		}
		spin_unlock_irqrestore(udc->lock, flags);

		ret = ci13xxx_exit_lpm(udc, true);
		if (ret) {
		dev_err(udc->transceiver->dev,
		"%s: Unable to exit lpm %d, ignore pullup\n",
		__func__, ret);
		return ret;
		}

		if (is_active)
		hw_device_state(udc->ep0out.qh.dma);
		else