[PATCH v3 12/12] PCI: rockchip-ep: Handle PERST# signal in endpoint mode

[Manivannan Sadhasivam]

On Fri, Oct 11, 2024 at 06:30:31PM +0900, Damien Le Moal wrote:
> On 10/10/24 19:49, Manivannan Sadhasivam wrote:
> >> +static int rockchip_pcie_ep_setup_irq(struct pci_epc *epc)
> >> +{
> >> +	struct rockchip_pcie_ep *ep = epc_get_drvdata(epc);
> >> +	struct rockchip_pcie *rockchip = &ep->rockchip;
> >> +	struct device *dev = rockchip->dev;
> >> +	int ret;
> >> +
> >> +	if (!rockchip->ep_gpio)
> >> +		return 0;
> >> +
> >> +	/* PCIe reset interrupt */
> >> +	ep->perst_irq = gpiod_to_irq(rockchip->ep_gpio);
> >> +	if (ep->perst_irq < 0) {
> >> +		dev_err(dev, "No corresponding IRQ for PERST GPIO\n");
> >> +		return ep->perst_irq;
> >> +	}
> >> +
> >> +	ep->perst_asserted = true;
> > 
> > How come?
> 
> Yeah, a bit confusing. This is because the gpio active low / inactive high, so
> as soon as we enable the IRQ, we are going to get one IRQ even though perst gpio
> signal has not changed yet.

Which means you are looking for a wrong level! What is the polarity of the
PERST# gpio in DT?

- Mani

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