Messages in this thread |  | | From | Crt Mori <> | | Date | Tue, 5 May 2026 09:48:00 +0200 | | Subject | Re: [PATCH] iio: mlx90614: fix missing GPIO direction return value checks |
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On Tue, 5 May 2026 at 09:31, Salah Triki <salah.triki@gmail.com> wrote: > > On Tue, Apr 28, 2026 at 06:33:05PM +0200, Crt Mori wrote: > > On Tue, 28 Apr 2026 at 18:04, Jonathan Cameron <jic23@kernel.org> wrote: > > > > > > On Tue, 28 Apr 2026 09:38:47 +0100 > > > Salah Triki <salah.triki@gmail.com> wrote: > > > > > > > On Tue, Apr 28, 2026 at 11:00:04AM +0300, Andy Shevchenko wrote: > > > > > On Mon, Apr 27, 2026 at 10:58:00PM +0100, Salah Triki wrote: > > > > > > The functions gpiod_direction_output() and gpiod_direction_input() can > > > > > > fail, but their return values were previously ignored. > > > > > > > > > > > > If an error occurs during the GPIO configuration, the function should > > > > > > abort the wake-up sequence and return the error code. More importantly, > > > > > > failing to check these values could lead to the I2C bus remaining > > > > > > locked if an error occurs after i2c_lock_bus() is called. > > > > > > > > > > > > Add return value checks and ensure the I2C bus is properly unlocked > > > > > > via a goto label in case of failure. > > > > > > > > > > ... > > > > > > > > > > > - gpiod_direction_output(data->wakeup_gpio, 0); > > > > > > + > > > > > > + ret = gpiod_direction_output(data->wakeup_gpio, 0); > > > > > > + if (ret) > > > > > > + goto out_unlock; > > > > > > + > > > > > > msleep(chip_info->wakeup_delay_ms); > > > > > > - gpiod_direction_input(data->wakeup_gpio); > > > > > > + > > > > > > + ret = gpiod_direction_input(data->wakeup_gpio); > > > > > > + if (ret) > > > > > > + goto out_unlock; > > > > > > > > > > While technically it sounds correct, the potential problem here is that you may > > > > > fail this in case CONFIG_GPIOLIB=n. Is this GPIO optional? > > > > > What may happen if GPIO is not optional, but for some reason setting it fails? > > > > > > > > > > TL;DR: > > > > > I am not sure about this patch. At least I'm not comfortable to take it without > > > > > testing on real HW. > > > > > > > > > > -- > > > > > With Best Regards, > > > > > Andy Shevchenko > > > > > > > > > > > > > > > > > > Thank you for your feedback. Since I don't have the physical hardware to > > > > perform the necessary tests and ensure there are no regressions, I agree > > > > that it is safer to drop this patch. I don't want to risk breaking the > > > > driver for a minor cleanup. > > > > > > > Maybe Crt has the hardware to test. For now I'll assume this is not > > > going anywhere wrt to tracking in patchwork. > > > > > I will dig the hardware to test as it was off my desk for some time > > now. It seems like backwards compatible, but I am wondering why would > > we want to be informed of this failing? The problem is that sensor > > uses wakeup line (same as for i2c) to receive wakeup pulse, so in > > theory this is already a workaround. @Salah did you see any issues in > > the wild? > > > > Thanks for digging out the hardware to test this! > > To answer your question: I haven't observed this failing in the wild on > this specific sensor. The patch was initially motivated by a static > analysis and general robustness cleanup, ensuring that we don't ignore > errors from gpiod_* functions (especially in the context of keeping the > I2C bus locked). > > However, as Andy pointed out, turning this into a fatal error might not > be desirable if the GPIO is optional or if the failure is transient on some > platforms. The goal was simply to improve visibility if the GPIO > configuration fails.
This GPIO in this case is basically used for generating wakeup pulse (so when sensor is sleeping) and I doubt there is usefulness of the GPIO error failure for this case from user perspective - there is a use case when debugging.
At the moment I am fairly busy. I have found the sensor, but I need to dig out the some board to port the latest kernel to. I hope I get a reminder from Jonathan as the window gets closed, but I also have trouble
> > Best Regards, > -- > Salah Triki
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