Re: [PATCH] i2c: i2c-gpio: fix some of gpio sleep issues

["Uwe Kleine-König" <u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

On Fri, Mar 27, 2015 at 04:46:09PM +0100, Wolfram Sang wrote:
> On Tue, Mar 17, 2015 at 12:04:29PM +0000, Ben Dooks wrote:
> > The i2c-gpio driver can be used in systems where the GPIO itself is
> > provided by a GPIO driver that may be sleeping (for example, SPI or
> > USB). In this case, it is preferable to use the _cansleep() variants
> > of the GPIO code.
> > 
> > We can only fix this up for the case where the i2c-gpio implementation
> > provides open-drain outputs as there are no gpio_direction_xxx_cansleep()
> > provided.
> > 
> > This removes the issues on the customer system with the console constantly
> > showing the following warning:
> > 
> > WARNING: CPU: 0 PID: 1 at drivers/gpio/gpiolib.c:2389 gpiod_set_raw_value
> 
> ??? It will silence a warning but will totally break the timing in case
> sleeping is needed? I'd think the warning is very suitable.
I don't understand this objection. What do you mean by "timing"? A
sleeping gpio is probably slower, but this shouldn't affect correctness
of the protocol implementation, should it?

Best regards
Uwe

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