On Wed, Sep 03, 2025 at 01:05:27PM +0200, Bartosz Golaszewski wrote: > On Wed, Sep 3, 2025 at 12:53 PM Andy Shevchenko > <andriy.shevchenko@xxxxxxxxx> wrote: > > On Wed, Sep 03, 2025 at 12:41:48PM +0200, Bartosz Golaszewski wrote: > > > On Wed, Sep 3, 2025 at 12:38 PM Andy Shevchenko > > > <andriy.shevchenko@xxxxxxxxx> wrote: > > > > On Wed, Sep 03, 2025 at 12:34:00PM +0200, Bartosz Golaszewski wrote: > > > > > On Wed, Sep 3, 2025 at 12:22 PM Andy Shevchenko > > > > > <andriy.shevchenko@xxxxxxxxx> wrote: > > > > > > On Wed, Sep 03, 2025 at 09:33:34AM +0200, Bartosz Golaszewski wrote: > > > > > > > On Tue, Sep 2, 2025 at 10:46 PM Andy Shevchenko > > > > > > > <andy.shevchenko@xxxxxxxxx> wrote: > > > > > > > > On Tue, Sep 2, 2025 at 8:42 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote: > > > > > > > > > On Tue, Sep 2, 2025 at 4:38 PM Andy Shevchenko > > > > > > > > > <andriy.shevchenko@xxxxxxxxx> wrote: > > > > > > > > > > On Tue, Sep 02, 2025 at 01:59:25PM +0200, Bartosz Golaszewski wrote: ... > > > > > > > > > > > The strict flag in struct pinmux_ops disallows the usage of the same pin > > > > > > > > > > > as a GPIO and for another function. Without it, a rouge user-space > > > > > > > > > > > process with enough privileges (or even a buggy driver) can request a > > > > > > > > > > > used pin as GPIO and drive it, potentially confusing devices or even > > > > > > > > > > > crashing the system. Set it globally for all pinctrl-msm users. > > > > > > > > > > > > > > > > > > > > How does this keep (or allow) I²C generic recovery mechanism to work? > > > > > > > > > > > > > > Anyway, what is your point? I don't think it has any impact on this. > > > > > > > > > > > > If we have a group of pins that are marked as I²C, and we want to use recovery > > > > > > via GPIOs, would it be still possible to request as GPIO when controller driver > > > > > > is in the strict mode? > > > > > > > > > > Yes, if you mark that function as a "GPIO" function in the pin > > > > > controller driver. > > > > > > > > How would it prevent from requesting from user space? > > > > > > It wouldn't, we don't discriminate between user-space and in-kernel > > > GPIO users. A function either is a GPIO or isn't. Can you point me to > > > the driver you're thinking about or is this a purely speculative > > > question? > > > > The recovery mechanism is in I²C core and many drivers use that. > > I'm not aware of Qualcomm drivers in particular. But mechanism is > > in use in I²C DesignWare which is distributed a lot among platforms, > > so using word 'purely' is incorrect, and word 'speculative' is a bit > > strong, but you can think of the issue coming later on when somebody > > does something like this. > > > > The same applies to the in-band wakeup UART mechanism. > > > > Which means that with this series we will relax it back anyway for > > the above mentioned cases. > > > > (Not sure, but SPI DesignWare requires programming SPI native chip selects even > > if the GPIO is used for that, this might have also some implications, but here > > it's for real 'purely speculative'.) > > The high-level answer is: yes, a pin that will be used by GPIOLIB > needs the function it's muxed to, to be marked as "GPIOable" in its > parent pin controller if it's strict. That's still better than the > current situation. > > I can imagine we could differentiate between in-kernel and user-space > users of GPIOs and then make it impossible for the latter to request > certain pins while they could still be requested in the kernel but > that's outside of the scope of this series. > > I don't see why this would stop these patches though, as they don't > break anything unless you decide to make your pin controller strict in > which situation you'd need to verify which functions can GPIOs anyway. It can't anyway, Linus already applied :-) -- With Best Regards, Andy Shevchenko
