Hi,
Roger Quadros <rogerq@xxxxxx> writes:
>>> @@ -497,8 +503,8 @@ static int dwc3_omap_probe(struct platform_device *pdev)
>>> /* check the DMA Status */
>>> reg = dwc3_omap_readl(omap->base, USBOTGSS_SYSCONFIG);
>>>
>>> - ret = devm_request_irq(dev, omap->irq, dwc3_omap_interrupt, 0,
>>> - "dwc3-omap", omap);
>>> + ret = devm_request_threaded_irq(dev, omap->irq, dwc3_omap_interrupt,
>>> + NULL, 0, "dwc3-omap", omap);
>>
>> if you're using threaded_irq, it's better to have a NULL top half and
>> valid bottom half.
>
> But in this case we don't need a bottom half as there is nothing to do :).
>
>>
>> In fact, since this will be shared, you could do a proper preparation
>> and on top half check if $this device generated the IRQ and
>> conditionally schedule the bottom half. Don't forget to mask device's
>> interrupts from top half so you can run without IRQF_ONESHOT.
>>
>
> Why do this at all if there is nothing to do in the bottom half?
oh, but there is :-)
The whole idea of threaded IRQs is that you spend as little time as
possible on top half and the (strong) recommendation is that you *only*
check if $this device generated the interrupt. Note that "checking if
$this device generated the interrupt" will be mandatory as soon as you
mark the IRQ line as shared ;-)
So here's how this should look like:
static irqreturn_t dwc3_omap_interrupt(int irq, void *_omap)
{
struct dwc3_omap *omap = _omap;
u32 reg;
reg = readl(IRQSTATUS)
if (reg) {
mask_interrupts(omap);
return IRQ_WAKE_THREAD;
}
return IRQ_HANDLED;
}
static irqreturn_t dwc3_omap_threaded_interrupt(int irq, void *_omap)
{
struct dwc3_omap *omap = _omap;
u32 reg;
spin_lock(&omap->lock);
reg = readl(IRQSTATUS);
if (reg & BIT0)
handle_bit_0(omap);
if (reg & BIT1)
handle_bit_1(omap);
unmask_interrupts(omap);
spin_unlock(&omap->lock);
return IRQ_HANDLED;
}
this will *always* behave well with RT and non-RT kernels. It also
allows for the user to change priorities on these interrupt handlers if
necessary.
--
balbi
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