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([2600:8803:e7e4:500:3548:c22e:ea52:dbc7]) by smtp.gmail.com with ESMTPSA id 5614622812f47-47c76935637sm17105945b6e.12.2026.05.09.13.36.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 09 May 2026 13:36:19 -0700 (PDT) Message-ID: <7ff89e1f-f5ef-461c-83af-18360ad5dab0@baylibre.com> Date: Sat, 9 May 2026 15:36:19 -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 v4 3/3] iio: adc: ti-ads1298: Remove unnecessary CONFIG2 write during init To: Md Shofiqul Islam , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Cc: jic23@kernel.org, mike.looijmans@topic.nl, nuno.sa@analog.com, andy@kernel.org, andriy.shevchenko@intel.com References: <20260509151959.3475-1-shofiqtest@gmail.com> <20260509151959.3475-4-shofiqtest@gmail.com> Content-Language: en-US From: David Lechner In-Reply-To: <20260509151959.3475-4-shofiqtest@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/9/26 10:19 AM, Md Shofiqul Islam wrote: > The driver was enabling the internal test signal (INT_TEST), double > amplitude (TEST_AMP), and fast frequency (TEST_FREQ_FAST) bits in > CONFIG2 during initialization. These bits activate an internal square > wave generator intended for device testing and calibration, not normal > ECG operation. > > CONFIG2 defaults to having only the RESERVED bit set after reset, which > is the correct value for normal operation. Remove the write entirely > since it would just be writing the reset default value. > > Suggested-by: Mike Looijmans > Signed-off-by: Md Shofiqul Islam > --- > drivers/iio/adc/ti-ads1298.c | 9 --------- > 1 file changed, 9 deletions(-) > > diff --git a/drivers/iio/adc/ti-ads1298.c b/drivers/iio/adc/ti-ads1298.c > index 186bda3087..8957e873e1 100644 > --- a/drivers/iio/adc/ti-ads1298.c > +++ b/drivers/iio/adc/ti-ads1298.c > @@ -615,15 +615,6 @@ static int ads1298_init(struct iio_dev *indio_dev) > if (!indio_dev->name) > return -ENOMEM; > > - /* Enable internal test signal, double amplitude, double frequency */ This is why comments should say why and not what. If the original author had a plan for this, we don't know what it was. I look at the datasheet and the driver. Seems OK since the test signals aren't used anywhere in the driver right now. > - ret = regmap_write(priv->regmap, ADS1298_REG_CONFIG2, > - ADS1298_MASK_CONFIG2_RESERVED | > - ADS1298_MASK_CONFIG2_INT_TEST | > - ADS1298_MASK_CONFIG2_TEST_AMP | > - ADS1298_MASK_CONFIG2_TEST_FREQ_FAST); > - if (ret) > - return ret; > - > val = ADS1298_MASK_CONFIG3_RESERVED; /* Must write 1 always */ > if (!priv->reg_vref) { > /* Enable internal reference */