On Mon, Sep 20, 2021 at 12:29:45PM +0530, Manivannan Sadhasivam wrote: > Add driver support for Qualcomm PCIe Endpoint controller driver based on > the Designware core with added Qualcomm specific wrapper around the > core. > ... > +static irqreturn_t qcom_pcie_ep_perst_irq_thread(int irq, void *data) > +{ > + struct qcom_pcie_ep *pcie_ep = data; > + struct dw_pcie *pci = &pcie_ep->pci; > + struct device *dev = pci->dev; > + u32 perst; > + > + perst = gpiod_get_value(pcie_ep->reset); > + if (perst) { > + dev_dbg(dev, "PERST asserted by host. Shutting down the PCIe link!\n"); > + qcom_pcie_perst_assert(pci); > + } else { > + dev_dbg(dev, "PERST de-asserted by host. Starting link training!\n"); > + qcom_pcie_perst_deassert(pci); > + } > + > + irq_set_irq_type(gpiod_to_irq(pcie_ep->reset), > + (perst ? IRQF_TRIGGER_HIGH : IRQF_TRIGGER_LOW)); 1) There are only a handful of instances of irq_set_irq_type() being used with IRQF_TRIGGER_* (all others use IRQ_TYPE_*). 2) Using irq_set_irq_type() in an IRQ handler is unusual and seems potentially racy. Almost all irq_set_irq_type() uses are in initialization or probe paths. I did see one similar use in an IRQ handler (rb532_pata_irq_handler()), but the rarity of this pattern makes me suspicious. > +static int qcom_pcie_ep_enable_irq_resources(struct platform_device *pdev, > + struct qcom_pcie_ep *pcie_ep) > +{ > + ... > + pcie_ep->perst_irq = gpiod_to_irq(pcie_ep->reset); > + irq_set_status_flags(pcie_ep->perst_irq, IRQ_NOAUTOEN); > + ret = devm_request_threaded_irq(&pdev->dev, pcie_ep->perst_irq, NULL, > + qcom_pcie_ep_perst_irq_thread, > + IRQF_TRIGGER_HIGH | IRQF_ONESHOT, > + "perst_irq", pcie_ep); The similar code in the tegra194 driver looks like this: tegra_pcie_config_ep devm_request_threaded_irq(tegra_pcie_ep_pex_rst_irq, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT) tegra_pcie_ep_pex_rst_irq if (gpiod_get_value(pcie->pex_rst_gpiod)) pex_ep_event_pex_rst_assert(pcie); else pex_ep_event_pex_rst_deassert(pcie); Could qcom work the same way by requesting the IRQ with "IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING" instead of "IRQF_TRIGGER_HIGH", and omitting the irq_set_irq_type()? I know rising/falling is edge-triggered and high/low is level-triggered, but surely qcom isn't completely unique in the way its IRQ is wired up?