On Mon, Apr 24, 2023 at 08:33:18AM +0200, Greg Kroah-Hartman wrote:
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@vger.kernel.org # 5.10.x Signed-off-by: William Breathitt Gray william.gray@linaro.org
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
Ah, the 5.4 and 5.10 patches are missing the IIO changes from the 4.19 patch. I'll adjust and resubmit these two patches.
William Breathitt Gray