Re: [PULL] IIO - First set of new drivers, core support and cleanups for the 4.5 cycle

[Jonathan Cameron <jic23@kernel.org>]

On 01/12/15 17:13, Greg KH wrote:
> On Sun, Nov 22, 2015 at 02:31:54PM +0000, Jonathan Cameron wrote:
>>
>> Hi Greg,
>>
>> When this one and the fixes set I sent a few minutes ago merge you curiously
>> get an issue with drivers/staging/iio/Kconfig.  The right resolution is
>> to dump all the dummy driver stuff.
>>
>> All the other changes related to that move and various automerge stuff that
>> occurs looks fine to me.
> 
> Thanks for the merge info, that helped.
> 
> But, I'm now getting these build warnings that I don't think we had
> before:
> 
> drivers/staging/iio/adc/mxs-lradc.c: In function ‘mxs_lradc_complete_touch_event’:
> drivers/staging/iio/adc/mxs-lradc.c:325:5: warning: large integer implicitly truncated to unsigned type [-Woverflow]
>      (((x) << LRADC_DELAY_TRIGGER_LRADCS_OFFSET) & \
>      ^
> drivers/staging/iio/adc/mxs-lradc.c:734:7: note: in expansion of macro ‘LRADC_DELAY_TRIGGER’
>        LRADC_DELAY_TRIGGER(1 << TOUCHSCREEN_VCHANNEL1) |
>        ^
>   LD [M]  drivers/staging/iio/accel/adis16201.o
> drivers/staging/iio/adc/mxs-lradc.c: In function ‘mxs_lradc_buffer_preenable’:
> drivers/staging/iio/adc/mxs-lradc.c:322:42: warning: large integer implicitly truncated to unsigned type [-Woverflow]
>  #define LRADC_DELAY_TRIGGER_LRADCS_MASK  (0xff << 24)
>                                           ^
> drivers/staging/iio/adc/mxs-lradc.c:1308:29: note: in expansion of macro ‘LRADC_DELAY_TRIGGER_LRADCS_MASK’
>   mxs_lradc_reg_clear(lradc, LRADC_DELAY_TRIGGER_LRADCS_MASK |
>                              ^
> drivers/staging/iio/adc/mxs-lradc.c: In function ‘mxs_lradc_buffer_postdisable’:
> drivers/staging/iio/adc/mxs-lradc.c:322:42: warning: large integer implicitly truncated to unsigned type [-Woverflow]
>  #define LRADC_DELAY_TRIGGER_LRADCS_MASK  (0xff << 24)
>                                           ^
> drivers/staging/iio/adc/mxs-lradc.c:1327:29: note: in expansion of macro ‘LRADC_DELAY_TRIGGER_LRADCS_MASK’
>   mxs_lradc_reg_clear(lradc, LRADC_DELAY_TRIGGER_LRADCS_MASK |
>                              ^
> 
> Can you fix those up?
> 
> thanks,
> 
> greg k-h
oops. I'd forgotten I got that one a while ago and meant to check what was causing
it - sorry about that - initially assumed it was just a warning that had gotten
turned on in the autobuilder.

After a lot of digging can be boiled down to statements
that end up as

(0xff << 24) | (1UL << 20)
Now I'm not entirely sure why it is unhappy with that. 
(0xffUL << 24) | (1UL << 20) is and (0xff << 24) | (1 << 20) - the original - is fine
as well.

The oddity to my mind is that 0xff is supposed to be fitted to the smallest possible
unsigned type (as it's in hex) so why is this happening?

Gah. Thoroughly irritating.

So possible fixes...

Revert the patch in question or add the UL to the 0xFF so that it's happy. 

Anyone with greater c knowledge than me want to suggest which is the 'right'
fix?

Jonathan