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

On 20.01.2017, at 05:23, Eduardo Valentin [off-list ref] wrote:

On Thu, Jan 19, 2017 at 08:14:02PM -0800, Eduardo Valentin wrote:

quoted

Hello Martin,

On Sat, Jan 07, 2017 at 04:55:45PM +0000, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote:

quoted

From: Martin Sperl <redacted>

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 <redacted>
Acked-by: Eric Anholt <redacted>
Acked-by: Stefan Wahren <redacted>

<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