On Sun, Apr 23, 2023 at 07:20:46PM -0400, William Breathitt Gray wrote:
> commit 4aa3b75c74603c3374877d5fd18ad9cc3a9a62ed upstream.
>
> The Counter (CNTR) register is 24 bits wide, but we can have an
> effective 25-bit count value by setting bit 24 to the XOR of the Borrow
> flag and Carry flag. The flags can be read from the FLAG register, but a
> race condition exists: the Borrow flag and Carry flag are instantaneous
> and could change by the time the count value is read from the CNTR
> register.
>
> Since the race condition could result in an incorrect 25-bit count
> value, remove support for 25-bit count values from this driver.
>
> Fixes: 28e5d3bb0325 ("iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8")
> Cc: <stable@xxxxxxxxxxxxxxx> # 5.10.x
> Signed-off-by: William Breathitt Gray <william.gray@xxxxxxxxxx>
> ---
> drivers/counter/104-quad-8.c | 18 +++---------------
> 1 file changed, 3 insertions(+), 15 deletions(-)
This patch breaks the build:
CC [M] drivers/counter/104-quad-8.o
drivers/counter/104-quad-8.c: In function ‘quad8_read_raw’:
drivers/counter/104-quad-8.c:117:34: error: ‘QUAD8_FLAG_BT’ undeclared (first use in this function); did you mean ‘QUAD8_FLAG_E’?
117 | borrow = flags & QUAD8_FLAG_BT;
| ^~~~~~~~~~~~~
| QUAD8_FLAG_E
drivers/counter/104-quad-8.c:117:34: note: each undeclared identifier is reported only once for each function it appears in
drivers/counter/104-quad-8.c:118:36: error: ‘QUAD8_FLAG_CT’ undeclared (first use in this function); did you mean ‘QUAD8_FLAG_E’?
118 | carry = !!(flags & QUAD8_FLAG_CT);
| ^~~~~~~~~~~~~
| QUAD8_FLAG_E
