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

[Sergei Shtylyov <sergei.shtylyov-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org>]

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-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
> 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(-)

> 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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