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

On Mon, 15 Dec 2014 13:34:56 +0000
David Laight [off-list ref] wrote:

From: Sergei Shtylyov

quoted

Hello.

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

quoted

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

quoted

Reported-by: Patrice VILCHEZ <redacted>
Signed-off-by: Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
---
  drivers/usb/gadget/udc/atmel_usba_udc.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

quoted

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?

Better still remember the written value in one of the structures so
that it doesn't have to be read at all.

Sure, I'll modify the code accordingly.

Thanks,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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