lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 27 May 2020 18:08:46 -0700 From: Stephen Boyd <swboyd@...omium.org> To: Maulik Shah <mkshah@...eaurora.org>, bjorn.andersson@...aro.org, evgreen@...omium.org, linus.walleij@...aro.org, maz@...nel.org, mka@...omium.org Cc: linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, linux-gpio@...r.kernel.org, agross@...nel.org, tglx@...utronix.de, jason@...edaemon.net, dianders@...omium.org, rnayak@...eaurora.org, ilina@...eaurora.org, lsrao@...eaurora.org Subject: Re: [PATCH v2 1/4] gpio: gpiolib: Allow GPIO IRQs to lazy disable Quoting Maulik Shah (2020-05-27 04:26:14) > On 5/27/2020 3:14 PM, Stephen Boyd wrote: > > Quoting Maulik Shah (2020-05-23 10:11:10) > >> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > >> index eaa0e20..3810cd0 100644 > >> --- a/drivers/gpio/gpiolib.c > >> +++ b/drivers/gpio/gpiolib.c > >> @@ -2465,32 +2465,37 @@ static void gpiochip_irq_relres(struct irq_data *d) > >> gpiochip_relres_irq(gc, d->hwirq); > >> } > >> > >> +static void gpiochip_irq_mask(struct irq_data *d) > >> +{ > >> + struct gpio_chip *gc = irq_data_get_irq_chip_data(d); > >> + > >> + if (gc->irq.irq_mask) > >> + gc->irq.irq_mask(d); > >> + gpiochip_disable_irq(gc, d->hwirq); > > How does this work in the lazy case when I want to drive the GPIO? Say I > > have a GPIO that is also an interrupt. The code would look like > > > > struct gpio_desc *gpio = gpiod_get(...) > > unsigned int girq = gpiod_to_irq(gpio) > > > > request_irq(girq, ...); > > > > disable_irq(girq); > > gpiod_direction_output(gpio, 1); > > > > In the lazy case genirq wouldn't call the mask function until the first > > interrupt arrived on the GPIO line. If that never happened then wouldn't > > we be blocked in gpiod_direction_output() when the test_bit() sees > > FLAG_USED_AS_IRQ? Or do we need irqs to be released before driving > > gpios? > > The client driver can decide to unlazy disable IRQ with below API... > > irq_set_status_flags(girq, IRQ_DISABLE_UNLAZY); > > This will immediatly invoke mask function (unlazy disable) from genirq, > even though irq_disable is not implemented. > Sure a consumer can disable the lazy feature, but that shouldn't be required to make this work. The flag was introduced in commit e9849777d0e2 ("genirq: Add flag to force mask in disable_irq[_nosync]()") specifically to help devices that can't disable the interrupt in their own device avoid a double interrupt.
Powered by blists - more mailing lists