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Sat, 21 Dec 2024 21:56:37 -0800 (PST) Received: from localhost ([2804:30c:4057:c200:dfe2:5075:a83a:1a44]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-72aad8157f9sm5808035b3a.24.2024.12.21.21.56.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Dec 2024 21:56:37 -0800 (PST) Date: Sun, 22 Dec 2024 02:57:13 -0300 From: Marcelo Schmitt To: Esteban Blanc Cc: Lars-Peter Clausen , Michael Hennerich , Nuno =?iso-8859-1?Q?S=E1?= , Jonathan Cameron , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jonathan Corbet , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v2 2/6] iio: adc: ad4030: add driver for ad4030-24 Message-ID: References: <20241219-eblanc-ad4630_v1-v2-0-f36e55907bf5@baylibre.com> <20241219-eblanc-ad4630_v1-v2-2-f36e55907bf5@baylibre.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241219-eblanc-ad4630_v1-v2-2-f36e55907bf5@baylibre.com> Hello Esteban, some comments inline. On 12/19, Esteban Blanc wrote: > This adds a new driver for the Analog Devices INC. AD4030-24 ADC. > > The driver implements basic support for the AD4030-24 1 channel > differential ADC with hardware gain and offset control. > > Signed-off-by: Esteban Blanc > --- [...] > + > +static int ad4030_spi_read(void *context, const void *reg, size_t reg_size, > + void *val, size_t val_size) > +{ > + int ret; > + struct ad4030_state *st = context; > + struct spi_transfer xfer = { > + .tx_buf = st->tx_data, > + .rx_buf = st->rx_data.raw, > + .len = reg_size + val_size, > + .speed_hz = AD4030_SPI_MAX_REG_XFER_SPEED, Is speed_hz really needed? What happens if the controller can't clock at 80MHz? > + }; > + > + if (xfer.len > ARRAY_SIZE(st->tx_data) || > + xfer.len > ARRAY_SIZE(st->rx_data.raw)) > + return -EINVAL; Would it make sense to bring register configuration mode commands into the regmap calls? I mean, to do the ad4030_enter_config_mode() transfer here and the ad4030_exit_config_mode() at the end of this function. >From datasheet, it looks like both enter/exit config mode are required for reg access so why not doing them in the regmap callbacks? With that, I think it won't be needed to call register config mode functions in ad4030_single_conversion() and in buffer enable/disable functions. Might need implement regmap_config read and write callbacks to properly handle regmap_bulk_read/write interface. > + > + memset(st->tx_data, 0, ARRAY_SIZE(st->tx_data)); > + memcpy(st->tx_data, reg, reg_size); > + > + ret = spi_sync_transfer(st->spi, &xfer, 1); > + if (ret) > + return ret; > + > + memcpy(val, &st->rx_data.raw[reg_size], val_size); > + > + return ret; > +} > + [...] > + > +static int ad4030_get_chan_calibscale(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + int *val, > + int *val2) > +{ > + struct ad4030_state *st = iio_priv(indio_dev); > + u16 gain; > + int ret; > + > + ret = regmap_bulk_read(st->regmap, AD4030_REG_GAIN_CHAN(chan->address), > + st->rx_data.raw, AD4030_REG_GAIN_BYTES_NB); > + if (ret) > + return ret; > + > + gain = get_unaligned_be16(st->rx_data.raw); My impression is that it is a bit odd to handle endianness after/before calling regmap_read/write(). Can you try set .val_format_endian_default = REGMAP_ENDIAN_BIG, in ad4030_regmap_bus? If that doesn't help, what about doing the get/set_unaligned stuff within the bus read/write calls? > + > + /* From datasheet: multiplied output = input × gain word/0x8000 */ > + *val = gain / 0x8000; Use a define to give a name to the gain constant? > + *val2 = mul_u64_u32_div(gain % 0x8000, NANO, 0x8000); > + > + return IIO_VAL_INT_PLUS_NANO; > +} > + [...]