Hi,
Roger Quadros <rogerq@xxxxxx> writes:
>> 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;
>
> This should be IRQ_NONE right?
possibly, testing will say ;-)
>> static irqreturn_t dwc3_omap_threaded_interrupt(int irq, void *_omap)
>> {
>> struct dwc3_omap *omap = _omap;
>> u32 reg;
>>
>> spin_lock(&omap->lock);
>
> Do we really need a spin_lock for the dwc3-omap driver?
> Currently we won't be doing anything other than just
> clearing the irqstatus and re-enabling the interrupts.
well, if there's no possibility of races, then no. But only testing will
say for sure, I guess. I didn't really go through the entire thing just
to a write a quick little template :-p
--
balbi
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