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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429c1142e7dsm2605837f8f.17.2025.10.31.02.43.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Oct 2025 02:43:38 -0700 (PDT) Date: Fri, 31 Oct 2025 09:43:36 +0000 From: David Laight To: Andy Shevchenko Cc: Jonathan Cameron , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Jyoti Bhayana , Jonathan Cameron , David Lechner , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko Subject: Re: [PATCH v1 1/1] iio: common: scmi_sensors: Replace const_ilog2() with ilog2() Message-ID: <20251031094336.6f352b4f@pumpkin> In-Reply-To: <20251031074500.3958667-1-andriy.shevchenko@linux.intel.com> References: <20251031074500.3958667-1-andriy.shevchenko@linux.intel.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 31 Oct 2025 08:45:00 +0100 Andy Shevchenko wrote: > const_ilog2() was a workaround of some sparse issue, which was > never appeared in the C functions. Replace it with ilog2(). > > Signed-off-by: Andy Shevchenko > --- > drivers/iio/common/scmi_sensors/scmi_iio.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/iio/common/scmi_sensors/scmi_iio.c b/drivers/iio/common/scmi_sensors/scmi_iio.c > index 39c61c47022a..b40c6d6442e6 100644 > --- a/drivers/iio/common/scmi_sensors/scmi_iio.c > +++ b/drivers/iio/common/scmi_sensors/scmi_iio.c > @@ -69,7 +69,7 @@ static int scmi_iio_sensor_update_cb(struct notifier_block *nb, > * Converting the timestamp to nanoseconds below. > */ > tstamp_scale = sensor->sensor_info->tstamp_scale + > - const_ilog2(NSEC_PER_SEC) / const_ilog2(10); > + ilog2(NSEC_PER_SEC) / ilog2(10); Is that just a strange way of writing 9 ? Mathematically log2(x)/log2(10) is log10(x) - which would be 9. The code does seem to be 'in luck' though. NSEC_PER_SEC is 10^9 or 0x3b9aca00, so ilog2(NSEC_PER_SEC) is 29. ilog2(10) is 3, and 29/3 is 9. Do the same for 10^10 and you get 11. David > if (tstamp_scale < 0) { > do_div(time, int_pow(10, abs(tstamp_scale))); > time_ns = time;