From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <57D0584E.2000709@parrot.com> Date: Wed, 7 Sep 2016 20:11:26 +0200 From: Gregor Boirie MIME-Version: 1.0 To: Jonathan Cameron , Lars-Peter Clausen , CC: Hartmut Knaack , Peter Meerwald-Stadler Subject: Re: [PATCH v1 1/1] iio:core: fix IIO_VAL_FRACTIONAL sign handling References: <32c015f4-bbd7-e2f4-3b4c-f7799ea95360@metafoo.de> <419daee6-1e68-dba4-3e04-3c13d58eea44@kernel.org> In-Reply-To: <419daee6-1e68-dba4-3e04-3c13d58eea44@kernel.org> Content-Type: text/plain; charset="windows-1252"; format=flowed List-ID: Just to mention that a somewhat similar patch might be needed to handle negative IIO_VAL_FRACTIONAL_LOG2 values. On 09/05/2016 10:24 PM, Jonathan Cameron wrote: > On 05/09/16 08:59, Lars-Peter Clausen wrote: >> On 09/03/2016 05:13 PM, Jonathan Cameron wrote: >>> On 02/09/16 19:27, Gregor Boirie wrote: >>>> 7985e7c100 ("iio: Introduce a new fractional value type") introduced a >>>> new IIO_VAL_FRACTIONAL value type meant to represent rational type numbers >>>> expressed by a numerator and denominator combination. >>>> >>>> Formating of IIO_VAL_FRACTIONAL values relies upon do_div() usage. This >>>> fails handling negative values properly since parameters are reevaluated >>>> as unsigned values. >>>> Fix this by using div_s64_rem() instead. Computed integer part will carry >>>> properly signed value. Formatted fractional part will always be positive. >>>> >>>> Fixes: 7985e7c100 ("iio: Introduce a new fractional value type") >>>> Signed-off-by: Gregor Boirie >>> Hi Gregor, >>> >>> While this looks sensible to me, I always gain an almighty headache when >>> I hit the various divide functions. >>> >>> Lars, the fractional code was yours in the first place. >>> If you have time can you sanity check this please. >> Looks good. While looking into this I noticed that we have a very similar >> patch[1] in our tree, seems like somebody forgot to send that upstream. >> >> Reviewed-by: Lars-Peter Clausen > Applied to the fixes-togreg branch of iio.git and marked for stable. > Good to know about the previous patch - if there was anything hiding around > this I would assume that would have shaken it out by now! > > Thanks > > Jonathan >> >> [1] >> https://github.com/analogdevicesinc/linux/commit/1dbcdcfd0c8d3f5513572697685d9f30ba49d851 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >>