Re: [PATCH 4/4] usb: atmel_usba_udc: mask status with enabled irqs

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Hello.

On 12/15/2014 4:03 PM, Boris Brezillon wrote:

Avoid interpreting useless status flags when we're not waiting for such
events by masking the status variable with the interrupt enabled register
value.

Reported-by: Patrice VILCHEZ <patrice.vilchez@xxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
---
  drivers/usb/gadget/udc/atmel_usba_udc.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/atmel_usba_udc.c b/drivers/usb/gadget/udc/atmel_usba_udc.c
index 55c8dde..bc3a532 100644
--- a/drivers/usb/gadget/udc/atmel_usba_udc.c
+++ b/drivers/usb/gadget/udc/atmel_usba_udc.c
@@ -1612,12 +1612,14 @@ static irqreturn_t usba_udc_irq(int irq, void *devid)

  	spin_lock(&udc->lock);

-	status = usba_readl(udc, INT_STA);
+	status = usba_readl(udc, INT_STA) & usba_readl(udc, INT_ENB);
  	DBG(DBG_INT, "irq, status=%#08x\n", status);

  	if (status & USBA_DET_SUSPEND) {
  		toggle_bias(udc, 0);
  		usba_writel(udc, INT_CLR, USBA_DET_SUSPEND);
+		usba_writel(udc, INT_ENB,
+			    usba_readl(udc, INT_ENB) | USBA_WAKE_UP);
  		udc->bias_pulse_needed = true;
  		DBG(DBG_BUS, "Suspend detected\n");
  		if (udc->gadget.speed != USB_SPEED_UNKNOWN
@@ -1631,6 +1633,8 @@ static irqreturn_t usba_udc_irq(int irq, void *devid)
  	if (status & USBA_WAKE_UP) {
  		toggle_bias(udc, 1);
  		usba_writel(udc, INT_CLR, USBA_WAKE_UP);
+		usba_writel(udc, INT_ENB,
+			    usba_readl(udc, INT_ENB) & ~USBA_WAKE_UP);
  		DBG(DBG_BUS, "Wake Up CPU detected\n");
  	}

Looks like t make sense to read the INT_ENB register into a separate variable, to save on extra reads?

WBR, Sergei

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