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([2600:8803:e7e4:500:a950:74e5:81f2:8c89]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7ebcae20782sm9133072a34.4.2026.07.11.08.22.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 11 Jul 2026 08:22:49 -0700 (PDT) Message-ID: Date: Sat, 11 Jul 2026 10:22:48 -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 v7 7/7] iio: dac: ad5686: add gain control support To: rodrigo.alencar@analog.com, Michael Auchter , linux@analog.com, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Cc: Michael Hennerich , Jonathan Cameron , Andy Shevchenko , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Philipp Zabel , Kees Cook , "Gustavo A. R. Silva" References: <20260710-ad5686-new-features-v7-0-1bcc8c280e4d@analog.com> <20260710-ad5686-new-features-v7-7-1bcc8c280e4d@analog.com> Content-Language: en-US From: David Lechner In-Reply-To: <20260710-ad5686-new-features-v7-7-1bcc8c280e4d@analog.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/10/26 6:20 AM, Rodrigo Alencar via B4 Relay wrote: > From: Rodrigo Alencar > > Most of the supported devices rely on a GAIN pin to control a 2x > multiplier applied to the output voltage. Other devices, e.g. the > single-channel ones, provides a gain control through a bit field in > the control register. Some designs might have the GAIN pin hardwired > to VDD/VLOGIC or GND, which would have no "gain-gpios" device property, > being able to set "adi,range-double" if it is hardwired to VDD. The > vref_mv field is moved down in the struct ad5686_state, so that the > overall size increase is reduced. > ... > @@ -217,6 +229,82 @@ static int ad5686_write_raw(struct iio_dev *indio_dev, > > return ad5686_write(st, AD5686_CMD_WRITE_INPUT_N_UPDATE_N, > chan->address, val << chan->scan_type.shift); > + case IIO_CHAN_INFO_SCALE: > + if (val == st->scale_avail[0] && val2 == st->scale_avail[1]) > + double_scale = false; > + else if (val == st->scale_avail[2] && val2 == st->scale_avail[3]) > + double_scale = true; > + else > + return -EINVAL; > + > + if (st->double_scale == double_scale) > + return 0; /* no change */ > + > + if (st->chip_info->regmap_type == AD5686_REGMAP && !st->gain_gpio) This condition is used a couple of times. It could be nice to just add a st->pin_strapped_gain field to make it self-documenting and use that instead. > + return -EINVAL; /* GAIN pin is board-strapped */ > + > + st->double_scale = double_scale; > + switch (st->chip_info->regmap_type) { > + case AD5310_REGMAP: > + ret = ad5310_control_sync(st); > + break; > + case AD5683_REGMAP: > + ret = ad5683_control_sync(st); > + break; > + case AD5686_REGMAP: > + ret = gpiod_set_value_cansleep(st->gain_gpio, > + st->double_scale ? 1 : 0); > + break; > + default: > + ret = -EINVAL; > + } > + if (ret) > + st->double_scale = !double_scale; /* revert on failure */ > + return ret; > + default: > + return -EINVAL; > + } > +} > +