Re: [PATCH 2/5] power: supply: bd71828: Fix current direction
Matti Vaittinen <[email protected]>
| Newsgroups | org.kernel.vger.linux-pm,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
On 12/08/2026 12:30, Andy Shevchenko wrote: > On Wed, Aug 12, 2026 at 10:25:36AM +0200, Andreas Kemnade wrote: >> On Wed, 12 Aug 2026 11:17:36 +0300 >> Andy Shevchenko <[email protected]> wrote: >>> On Wed, Aug 12, 2026 at 10:10:50AM +0200, Andreas Kemnade wrote: >>>> On Mon, 10 Aug 2026 13:09:07 +0300 >>>> Matti Vaittinen <[email protected]> wrote: > > ... > >>>> That code is complicated. What about a generic 16bit non_2complemented sign >>>> to 2-complemented sign function/macro. Such would have prevented the error >>>> in the first places. So &vals[i] = signbit_to_2complement(be16_to_cpu(tmp_curr), 15) * pwr->curr_factor >>> >>> Do you mean existing sign_extend32() from bitops.h? >>> >> >> I don't think it does what is needed. Here we have >> >> 0000 0000 0000 0001 -> 1 >> Usually we have >> >> 1111 1111 1111 1111 -> -1 >> >> but here >> >> 1000 0000 0000 0001 -> -1 > > I see, wouldn't this be then as simple as > > sign = $REGVAL & BIT(15 /* sign bit */); > if (sign) > $REGVAL = sign - $REGVAL; I find this more confusing than the current idea, which effectively is: if (sign) val = val_without_sign * -1; else val = val_without_sign (* 1); (I can't straight away say if "$REGVAL = sign - $REGVAL;" yields same result.) Yours, -- Matti -- Matti Vaittinen Linux kernel developer at ROHM Semiconductors Oulu Finland ~~ When things go utterly wrong vim users can always type :help! ~~