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Commit b11e94d0 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Felipe Balbi
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usb: musb: read MUSB_POWER register only when required. 



This is part of the workaround for AM35x advisory Advisory 1.1.20.
The advisory says that the IPSS bridge can't handle 8 & 16 bit read
access. An 8bit read access to MUSB_POWER results in an 32bit read
access which also reads INTRTX and therefore may lose interrupts.
This patch tries to minimize reads to MUSB_POWER and perform them only
when required.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
parent 4b0de6f3

drivers/usb/musb/musb_core.c

+8 −7
Original line number Diff line number Diff line
@@ -467,12 +467,12 @@ void musb_hnp_stop(struct musb *musb) 
 */



static irqreturn_t musb_stage0_irq(struct musb *musb, u8 int_usb,

				u8 devctl, u8 power)

				u8 devctl)

{

	struct usb_otg *otg = musb->xceiv->otg;

	irqreturn_t handled = IRQ_NONE;



	dev_dbg(musb->controller, "<== Power=%02x, DevCtl=%02x, int_usb=0x%x\n", power, devctl,

	dev_dbg(musb->controller, "<== DevCtl=%02x, int_usb=0x%x\n", devctl,

		int_usb);



	/* in host mode, the peripheral may issue remote wakeup.
@@ -485,6 +485,7 @@ static irqreturn_t musb_stage0_irq(struct musb *musb, u8 int_usb, 


		if (devctl & MUSB_DEVCTL_HM) {

			void __iomem *mbase = musb->mregs;

			u8 power;



			switch (musb->xceiv->state) {

			case OTG_STATE_A_SUSPEND:
@@ -492,6 +493,7 @@ static irqreturn_t musb_stage0_irq(struct musb *musb, u8 int_usb, 
				 * will stop RESUME signaling

				 */



				power = musb_readb(musb->mregs, MUSB_POWER);

				if (power & MUSB_POWER_SUSPENDM) {

					/* spurious */

					musb->int_usb &= ~MUSB_INTR_SUSPEND;
@@ -655,8 +657,8 @@ static irqreturn_t musb_stage0_irq(struct musb *musb, u8 int_usb, 
	}



	if (int_usb & MUSB_INTR_SUSPEND) {

		dev_dbg(musb->controller, "SUSPEND (%s) devctl %02x power %02x\n",

			otg_state_string(musb->xceiv->state), devctl, power);

		dev_dbg(musb->controller, "SUSPEND (%s) devctl %02x\n",

			otg_state_string(musb->xceiv->state), devctl);

		handled = IRQ_HANDLED;



		switch (musb->xceiv->state) {
@@ -1560,12 +1562,11 @@ static irqreturn_t generic_interrupt(int irq, void *__hci) 
irqreturn_t musb_interrupt(struct musb *musb)

{

	irqreturn_t	retval = IRQ_NONE;

	u8		devctl, power;

	u8		devctl;

	int		ep_num;

	u32		reg;



	devctl = musb_readb(musb->mregs, MUSB_DEVCTL);

	power = musb_readb(musb->mregs, MUSB_POWER);



	dev_dbg(musb->controller, "** IRQ %s usb%04x tx%04x rx%04x\n",

		(devctl & MUSB_DEVCTL_HM) ? "host" : "peripheral",
@@ -1576,7 +1577,7 @@ irqreturn_t musb_interrupt(struct musb *musb) 
	 */

	if (musb->int_usb)

		retval |= musb_stage0_irq(musb, musb->int_usb,

				devctl, power);

				devctl);



	/* "stage 1" is handling endpoint irqs */