Re: [PATCH V9] thermal: bcm2835: add thermal driver for bcm2835 soc

[kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org]

> On 20.01.2017, at 05:23, Eduardo Valentin <edubezval-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> 
> On Thu, Jan 19, 2017 at 08:14:02PM -0800, Eduardo Valentin wrote:
>> Hello Martin,
>> 
>> On Sat, Jan 07, 2017 at 04:55:45PM +0000, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote:
>>> From: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
>>> 
>>> Add basic thermal driver for bcm2835 SOC.
>>> 
>>> This driver currently relies on the firmware setting up the
>>> tsense HW block and does not set it up itself.
>>> 
>>> Signed-off-by: Martin Sperl <kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org>
>>> Acked-by: Eric Anholt <eric-WhKQ6XTQaPysTnJN9+BGXg@public.gmane.org>
>>> Acked-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
>>> 
>> 
>> <cut>
> 
> 
> Also, I am getting this warn from sparse:
> drivers/thermal/bcm2835_thermal.c:110:16: warning: cast truncates bits
> from constant value (3ffffffffff00 becomes ffffff00)
> drivers/thermal/bcm2835_thermal.c:134:16: warning: cast truncates bits
> from constant value (3ffffffffff becomes ffffffff)
> 
> Have you seen this?

No, I have not checked sparse.

These values are defined via GENMASK on line 47 and 57 respectively
and should actually compute to the following values:
  for line 110 (line 47 has the define):
    GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS +     \
            BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
            BCM2835_TS_TSENSCTL_THOLD_SHIFT)
    = GENMASK(10 + 8 - 1, 8) 
    = GENMASK(17, 8)
    = (((~0UL) << (8)) & (~0UL >> (32 - 1 - (10 + 8 - 1))))
    = 0x3ff00
  for line 134 (line 57 has the define):
    GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS +     \
            BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
            BCM2835_TS_TSENSCTL_THOLD_SHIFT)
    = GENMASK(10 + 0 - 1, 0)
    = GENMASK(9, 0)
    = (((~0UL) << (0)) & (~0UL >> (32 - 1 - (10 + 0 - 1))))
    = 0x003ff

Note that the preprocessor expansions have been verified by
looking at the preprocessed driver source
(drivers/thermal/bcm2835_thermal.i)

I wonder why sparse is computing these GENMASK values as:
0x3ffffffffff00 and 0x3ffffffffff

Martin