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Message-ID: <02ad01d98a2b$4cd080e0$e67182a0$@trustnetic.com> Date: Fri, 19 May 2023 16:24:15 +0800 From: Jiawen Wu <jiawenwu@...stnetic.com> To: "'Andrew Lunn'" <andrew@...n.ch> Cc: "'Andy Shevchenko'" <andy.shevchenko@...il.com>, <netdev@...r.kernel.org>, <jarkko.nikula@...ux.intel.com>, <andriy.shevchenko@...ux.intel.com>, <mika.westerberg@...ux.intel.com>, <jsd@...ihalf.com>, <Jose.Abreu@...opsys.com>, <hkallweit1@...il.com>, <linux@...linux.org.uk>, <linux-i2c@...r.kernel.org>, <linux-gpio@...r.kernel.org>, <mengyuanlou@...-swift.com> Subject: RE: [PATCH net-next v8 6/9] net: txgbe: Support GPIO to SFP socket On Thursday, May 18, 2023 8:49 PM, Andrew Lunn wrote: > > > 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? > > That is your upstream IRQ, the interrupt indicating one of your GPIO > lines has changed state. > > > 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. > > Do you have one MSI-X dedicated for GPIOs. Or is it your general MAC > interrupt, and you need to read an interrupt controller register to > determine it was GPIOs which triggered the interrupt? > > If you are getting errors when removing the driver it means you are > missing some level of undoing what us done in probe. Are you sure > regmap_del_irq_chip() is being called on unload? > > > 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... > > That is probably some sort of naming issue. You might want to add some > prints in swnode_find_gpio() and gpiochip_find() to see what it is > looking for vs what the name actually is. It's true for the problem of name, but there is another problem. SFP driver has successfully got gpio_desc, then it failed to get gpio_irq from gpio_desc (with error return -517). I traced the function gpiod_to_irq(): gc = desc->gdev->chip; offset = gpio_chip_hwgpio(desc); if (gc->to_irq) { int retirq = gc->to_irq(gc, offset); /* Zero means NO_IRQ */ if (!retirq) return -ENXIO; return retirq; } 'gc->to_irq = gpiochip_to_irq' was set in [4]gpiochip_irqchip_add_domain(). So: static int gpiochip_to_irq(struct gpio_chip *gc, unsigned int offset) { struct irq_domain *domain = gc->irq.domain; #ifdef CONFIG_GPIOLIB_IRQCHIP /* * Avoid race condition with other code, which tries to lookup * an IRQ before the irqchip has been properly registered, * i.e. while gpiochip is still being brought up. */ if (!gc->irq.initialized) return -EPROBE_DEFER; #endif gc->irq.initialized is set to true at the end of [3]gpiochip_add_irqchip() only. Firstly, it checks if irqchip is NULL: static int gpiochip_add_irqchip(struct gpio_chip *gc, struct lock_class_key *lock_key, struct lock_class_key *request_key) { struct fwnode_handle *fwnode = dev_fwnode(&gc->gpiodev->dev); struct irq_chip *irqchip = gc->irq.chip; unsigned int type; unsigned int i; if (!irqchip) return 0; The result shows that it was NULL, so gc->irq.initialized = false. Above all, return irq = -EPROBE_DEFER. So let's sort the function calls. In chronological order, [1] calls [2], [2] calls [3], then [1] calls [4]. The irq_chip was added to irq_domain->host_data->irq_chip before [1]. But I don't find where to convert gpio_chip->irq.domain->host_data->irq_chip to gpio_chip->irq.chip, it seems like it should happen after [4] ? But if it wants to use 'gc->to_irq' successfully, it should happen before [3]? [1] gpio_regmap_register() [2] gpiochip_add_data() [3] gpiochip_add_irqchip() [4] gpiochip_irqchip_add_domain() I'm sorry that I described the problem in a confusing way, apologize if I missed some code that caused this confusion.
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