Re: [PATCH v1] gpiolib: Respect error code of ->get_direction()

[Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>]

On Mon, 2018-07-09 at 15:13 +0200, Linus Walleij wrote:
> On Tue, Jul 3, 2018 at 2:38 AM Andy Shevchenko
> <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> 
> > In case we try to lock GPIO pin as IRQ when something going wrong
> > we print a misleading message.
> > 
> > Correct this by checking an error code from ->get_direction() in
> > gpiochip_lock_as_irq() and printing a corresponding message.
> > 
> > Note, this doesn't change overall behavior because error code used
> > to
> > be recognized as direction output which anyway led to an abortion of
> > request.
> > 
> > Fixes: 9c10280d85c1 ("gpio: flush direction status in
> > gpiochip_lock_as_irq()")
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> 
> OK per followup I stripped the Fixes tag and the last paragraph and
> applied.

Thanks!

> I am a bit worried that there might be platforms that have survived
> by igoring any error code from get direction (interpreting it as
> "input) but they will hopefully notice ... thanks to the new error
> print.

And then suddenly they might get no interrupt b/c pin, for example,
still an output (should be caught by other API calls I think, though
failing earlier is better for my opinion).

> 
> Did you look around to see if some driver might be returning
> error codes from get_direction()? I suspect mostly I2C-based
> expanders and if it's an error it's an error and this is the right
> thing to 
> do but you never know what people are doing...

In the GPIO/pinctrl folders: both tegras, bcm2835, stm32 and most of
Intel.

In the drivers: i2c-mux-ltc4306.

So, not many.

-- 
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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