On Wednesday, May 17, 2023 11:01 PM, Andrew Lunn wrote: > On Wed, May 17, 2023 at 10:55:01AM +0800, Jiawen Wu wrote: > > > > > > + gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL); > > > > > > + if (!gc) > > > > > > + return -ENOMEM; > > > > > > + > > > > > > + gc->label = devm_kasprintf(dev, GFP_KERNEL, "txgbe_gpio-%x", > > > > > > + (wx->pdev->bus->number << 8) | wx->pdev->devfn); > > > > > > + gc->base = -1; > > > > > > + gc->ngpio = 6; > > > > > > + gc->owner = THIS_MODULE; > > > > > > + gc->parent = dev; > > > > > > + gc->fwnode = software_node_fwnode(txgbe->nodes.group[SWNODE_GPIO]); > > > > > > > > > > Looking at the I²C case, I'm wondering if gpio-regmap can be used for this piece. > > > > > > > > I can access this GPIO region directly, do I really need to use regmap? > > > > > > It's not a matter of access, it's a matter of using an existing > > > wrapper that will give you already a lot of code done there, i.o.w. > > > you don't need to reinvent a wheel. > > > > I took a look at the gpio-regmap code, when I call devm_gpio_regmap_register(), > > I should provide gpio_regmap_config.irq_domain if I want to add the gpio_irq_chip. > > But in this use, GPIO IRQs are requested by SFP driver. How can I get irq_domain > > before SFP probe? And where do I add IRQ parent handler? > > I _think_ you are mixing upstream IRQs and downstream IRQs. > > Interrupts are arranged in trees. The CPU itself only has one or two > interrupts. e.g. for ARM you have FIQ and IRQ. When the CPU gets an > interrupt, you look in the interrupt controller to see what external > or internal interrupt triggered the CPU interrupt. And that interrupt > controller might indicate the interrupt came from another interrupt > controller. Hence the tree structure. And each node in the tree is > considered an interrupt domain. > > A GPIO controller can also be an interrupt controller. It has an > upstream interrupt, going to the controller above it. And it has > downstream interrupts, the GPIO lines coming into it which can cause > an interrupt. And the GPIO interrupt controller is a domain. > > So what exactly does gpio_regmap_config.irq_domain mean? Is it the > domain of the upstream interrupt controller? Is it an empty domain > structure to be used by the GPIO interrupt controller? It is very > unlikely to have anything to do with the SFP devices below it. Sorry, since I don't know much about interrupt, it is difficult to understand regmap-irq in a short time. There are many questions about regmap-irq. When I want to add an IRQ chip for regmap, for the further irq_domain, I need to pass a parameter of IRQ, and this IRQ will be requested with handler: regmap_irq_thread(). Which IRQ does it mean? In the previous code of using devm_gpiochip_add_data(), I set the MSI-X interrupt as gpio-irq's parent, but it was used to set chained handler only. Should the parent be this IRQ? I found the error with irq_free_descs and irq_domain_remove when I remove txgbe.ko. As you said, the interrupt of each tree node has its domain. Can I understand that there are two layer in the interrupt tree for MSI-X and GPIOs, and requesting them separately is not conflicting? Although I thought so, but after I implement gpio-regmap, SFP driver even could not find gpio_desc. Maybe I missed something on registering gpio-regmap... Anyway it is a bit complicated, could I use this version of GPIO implementation if it's really tough? Thanks.
