On 11/05/16 12:47, Felipe Balbi wrote: > > 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 > OK. Another hurdle I have is that how do I mask/unmask the interrupts? I do not see any masking bits, only enable/disable bits. I don't think we can use the enable/disable bits to mask as we'd loose events while the event is disabled. cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html