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

[Ben Dooks <ben.dooks-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org>]

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On 22/04/15 11:40, Ben Dooks wrote:
> On 27/03/15 17:46, 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.
> 
> This basically causes our system to fail to boot in any suitable
> time.
> 
> The problem is that the i2c bus is on the end of an SPI bus which
> means that the identification EEPROM tests and other items read
> from it will run through a gpio chip that is marked as 'can
> sleep'.
> 
> I don't have the exact times, but I got bored after the first
> thirty seconds of these log messages and immediately patched them
> out of the kernel.

Would a probe time warn and then doing the same change be ok?

- -- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius
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