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([2600:8803:e7e4:500:12a0:9178:ab4:39cc]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7e367d8fd96sm3817633a34.19.2026.05.09.15.09.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 09 May 2026 15:09:34 -0700 (PDT) Message-ID: <880e0d0c-da84-484e-869b-ff77454874e1@baylibre.com> Date: Sat, 9 May 2026 17:09:33 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] iio: magnetometer: add driver for MEMSIC MMC5983MA To: Vladislav Kulikov , jic23@kernel.org, nuno.sa@analog.com, andy@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260507205033.951990-1-vlad.kulikov.c@gmail.com> <20260507205033.951990-3-vlad.kulikov.c@gmail.com> Content-Language: en-US From: David Lechner In-Reply-To: <20260507205033.951990-3-vlad.kulikov.c@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/7/26 3:50 PM, Vladislav Kulikov wrote: > Add support for the MEMSIC MMC5983MA 3-axis magnetometer. The driver > provides raw magnetic field readings via IIO sysfs with SET/RESET > offset cancellation for each measurement. > > Signed-off-by: Vladislav Kulikov > --- I gave my RB tag already, but if we do another revision, a couple of suggestions. > +static int mmc5983_take_measurement(struct mmc5983_data *data, int m[3]) > +{ > + unsigned int status; > + u8 buf[7]; > + int ret; > + > + ret = regmap_write(data->regmap, MMC5983_REG_CTRL0, > + MMC5983_CTRL0_TM_M_BIT); > + if (ret) > + return ret; > + > + /* > + * Datasheet page 15: measurement time is 8 ms at BW=00 (default, > + * slowest setting). Use a 50 ms timeout for margin. > + */ > + ret = regmap_read_poll_timeout(data->regmap, MMC5983_REG_STATUS, > + status, > + status & MMC5983_STATUS_MEAS_M_DONE_BIT, > + 10000, 50000); I wouldn't mind seeing 10 * KILO, 50 * KILO here to make it easier to read. > + if (ret) > + return ret; > + > + ret = regmap_bulk_read(data->regmap, MMC5983_REG_XOUT0, buf, > + sizeof(buf)); > + if (ret) > + return ret; > + > + m[0] = (buf[0] << 10) | (buf[1] << 2) | ((buf[6] >> 6) & 0x3); > + m[1] = (buf[2] << 10) | (buf[3] << 2) | ((buf[6] >> 4) & 0x3); > + m[2] = (buf[4] << 10) | (buf[5] << 2) | ((buf[6] >> 2) & 0x3); > + > + return 0; > +} > + > +static int mmc5983_read_raw(struct iio_dev *indio_dev, > + const struct iio_chan_spec *chan, int *val, > + int *val2, long mask) > +{ > + struct mmc5983_data *data = iio_priv(indio_dev); > + int m1[3], m2[3]; > + int ret; > + > + switch (mask) { > + case IIO_CHAN_INFO_RAW: { > + guard(mutex)(&data->mutex); > + > + ret = regmap_write(data->regmap, MMC5983_REG_CTRL0, > + MMC5983_CTRL0_SET_BIT); > + if (ret) > + return ret; > + > + /* > + * Datasheet page 15: SET/RESET coil pulse is 500 ns. > + * Vendor sample code waits 500 us before the next operation. > + */ > + fsleep(500); > + > + ret = mmc5983_take_measurement(data, m1); > + if (ret) > + return ret; > + > + ret = regmap_write(data->regmap, MMC5983_REG_CTRL0, > + MMC5983_CTRL0_RESET_BIT); > + if (ret) > + return ret; > + > + /* > + * Datasheet page 15: SET/RESET coil pulse is 500 ns. > + * Vendor sample code waits 500 us before the next operation. > + */ > + fsleep(500); It looks like this SET/RESET sequence is also repeated during init. Maybe refactor that out into a separate function. > + > + ret = mmc5983_take_measurement(data, m2); > + if (ret) > + return ret; > + > + *val = (m1[chan->address] - m2[chan->address]) / 2; > + return IIO_VAL_INT; > + } > + case IIO_CHAN_INFO_SCALE: > + *val = 0; > + *val2 = 61035; > + return IIO_VAL_INT_PLUS_NANO; > + default: > + return -EINVAL; > + } > +} > +