On Sun, 2 Aug 2026 10:04:00 +0100 David Laight <[email protected]> wrote:
> On Sun, 2 Aug 2026 01:56:07 +0100 > Jonathan Cameron <[email protected]> wrote: > > > On Wed, 29 Jul 2026 09:25:38 +0100 > > Rodrigo Alencar via B4 Relay > > <[email protected]> wrote: > > > > > From: Rodrigo Alencar <[email protected]> > > > > > > Add parallel port support with amplitude, phase and frequency channels. > > > Those will be buffered capable channels, but only basic control of offset > > > and scale are implemented at this point. There are separate amplitude > > > and phase control for polar destination, which will provide different scan > > > types. Enabling and disabling of parallel mode will be implemented with > > > buffer setup ops or with update_scan_mode() once IIO backend integration > > > is in place. > > > > > > Signed-off-by: Rodrigo Alencar <[email protected]> > > Hmm. Curious... clang --version gives 22.1.8 on x86_64. > > > > make LLVM=1 LOCALVERSION= -j12 W=1 C=1 > > DESCEND objtool > > Documentation/.renames.txt: warning: ignored by one of the .gitignore files > > CC [M] drivers/iio/frequency/ad9910.o > > In file included from drivers/iio/frequency/ad9910.c:10: > > In file included from ./include/linux/clk.h:13: > > In file included from ./include/linux/kernel.h:26: > > In file included from ./include/linux/math.h:6: > > ./arch/x86/include/asm/div64.h:113:8: error: invalid operand for instruction > > 113 | asm ("addq %[add], %[lo]; adcq $0, %[hi]" : > > | ^ > > <inline asm>:1:7: note: instantiated into assembly here > > 1 | addq $2147483648, %rax; adcq $0, %rdx > > | ^~~~~~~~~~~~ > > 1 error generated. > > make[5]: *** [scripts/Makefile.build:289: drivers/iio/frequency/ad9910.o] > > Error 1 > > make[4]: *** [scripts/Makefile.build:549: drivers/iio/frequency] Error 2 > > make[3]: *** [scripts/Makefile.build:549: drivers/iio] Error 2 > > make[2]: *** [scripts/Makefile.build:549: drivers] Error 2 > > make[1]: *** [/home/jic23/src/kernel/iio/Makefile:2184: .] Error 2 > > make: *** [Makefile:248: __sub-make] Error 2 > > > > > > > --- > > > drivers/iio/frequency/ad9910.c | 154 > > > +++++++++++++++++++++++++++++++++++++++++ > > > 1 file changed, 154 insertions(+) > > > > > > diff --git a/drivers/iio/frequency/ad9910.c > > > b/drivers/iio/frequency/ad9910.c > > > index b41b011af281..aaeff2e7640e 100644 > > > --- a/drivers/iio/frequency/ad9910.c > > > +++ b/drivers/iio/frequency/ad9910.c > > > > > > > static int ad9910_read_raw(struct iio_dev *indio_dev, > > > @@ -691,6 +753,48 @@ static int ad9910_read_raw(struct iio_dev *indio_dev, > > > *val = 0; > > > *val2 = tmp64 >> 14; > > > return IIO_VAL_INT_PLUS_NANO; > > > + case AD9910_CHAN_IDX_PARALLEL_PHASE: > > > + *val = 0; > > > + *val2 = AD9910_PI_NANORAD >> 15; > > > + return IIO_VAL_INT_PLUS_NANO; > > > + case AD9910_CHAN_IDX_PARALLEL_FREQ: > > > + tmp32 = FIELD_GET(AD9910_CFR2_FM_GAIN_MSK, > > > + st->reg[AD9910_REG_CFR2].val32); > > > + tmp64 = (u64)st->data.sysclk_freq_hz << tmp32; > > > + tmp64 = ad9910_rational_scale(tmp64, NANO, > > > BIT_ULL(32)); > > > > Process of elimination points me to this line which is a slim wrapper. > > > > static inline u64 ad9910_rational_scale(u64 input, u64 scale, u64 reference) > > { > > return mul_u64_add_u64_div_u64(input, scale, reference >> 1, reference); > > } > > > > David, any thoughts? > > Lots of instructions only support sign extending 32bit immediates. > The asm constraint for the ADCQ needs to be "erm" not "irm". > I bet that is true elsewhere as well. > > See source/arch/x86/include/asm/div64.h line 114 > > I'm actually surprised you see it with clang - it usually prefers the "m" > constraint. > > I'll try to find a source tree that is clean enough to generate a patch. > Thanks! For anyone following along: https://lore.kernel.org/all/[email protected]/ Until David's fix is in a tree I'll hold off on merging this series. Given timing, that may unfortunately delay it a cycle, Jonathan > David > > > > > > For now I'm backing out the series. > > > > > + *val = div_s64_rem(tmp64, NANO, val2); > > > + return IIO_VAL_INT_PLUS_NANO; > > > + case AD9910_CHAN_IDX_PARALLEL_POLAR_AMP: > > > + tmp64 = (u64)st->data.output_current_uA * > > > + AD9910_NANO_MILLIAMP_PER_MICROAMP; > > > + *val = 0; > > > + *val2 = tmp64 >> 8; > > > + return IIO_VAL_INT_PLUS_NANO; > > > + case AD9910_CHAN_IDX_PARALLEL_POLAR_PHASE: > > > + *val = 0; > > > + *val2 = AD9910_PI_NANORAD >> 7; > > > + return IIO_VAL_INT_PLUS_NANO; > > > + default: > > > + return -EINVAL; > > > + } >
