On 11/05/2015 07:43 PM, Grygorii Strashko wrote: > diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c > index 6589e7e..31460f4 100644 > --- a/drivers/pci/host/pci-dra7xx.c > +++ b/drivers/pci/host/pci-dra7xx.c > @@ -302,8 +302,30 @@ static int __init dra7xx_add_pcie_port(struct dra7xx_pcie *dra7xx, > return -EINVAL; > } > > + /* > + * Mark dra7xx_pcie_msi IRQ as IRQF_NO_THREAD > + * On -RT and if kernel is booting with "threadirqs" cmd line parameter > + * the dra7xx_pcie_msi_irq_handler() will be forced threaded but, > + * in the same time, it's IRQ dispatcher and calls generic_handle_irq(), > + * which, in turn, will be resolved to handle_simple_irq() call. > + * The handle_simple_irq() expected to be called with IRQ disabled, as > + * result kernle will display warning: > + * "irq XXX handler YYY+0x0/0x14 enabled interrupts". > + * > + * Current DRA7 PCIe hw configuration supports 32 interrupts, > + * which cannot change because it's hardwired in silicon, and can assume > + * that only a few (most of the time it will be exactly ONE) of those > + * interrupts are pending at the same time. So, It's sane way to dial > + * with above issue by marking dra7xx_pcie_msi IRQ as IRQF_NO_THREAD. > + * if some platform will utilize a lot of MSI IRQs and will suffer > + * form -RT latencies degradation because of that - IRQF_NO_THREAD can > + * be removed and "Warning Annihilation" W/A can be applied [1] > + * > + * [1] https://lkml.org/lkml/2015/11/2/578 I don't think this novel is required. Also a reference to a patch which was not accepted is not a smart idea (since people might think they will improve their -RT latency by applying it without thinking). Do you have any *real* numbers where you can say this patch does better/worse than what you suggester earlier? I'm simply asking because each gpio-irq multiplexing driver does the same thing. > + */ > ret = devm_request_irq(&pdev->dev, pp->irq, > - dra7xx_pcie_msi_irq_handler, IRQF_SHARED, > + dra7xx_pcie_msi_irq_handler, > + IRQF_SHARED | IRQF_NO_THREAD, > "dra7-pcie-msi", pp); > if (ret) { > dev_err(&pdev->dev, "failed to request irq\n"); > Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
