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[2003:f6:ef1c:c500:ee59:d953:f148:40ba]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fac1598c1asm100202335ad.267.2024.07.03.03.38.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Jul 2024 03:38:42 -0700 (PDT) Message-ID: Subject: Re: [PATCH v3] iio: adc: ad7606: remove frstdata check for serial mode From: Nuno =?ISO-8859-1?Q?S=E1?= To: Guillaume Stols , Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , Greg Kroah-Hartman Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Cameron , jstephan@baylibre.com, dlechner@baylibre.com Date: Wed, 03 Jul 2024 12:42:31 +0200 In-Reply-To: <20240702-cleanup-ad7606-v3-1-18d5ea18770e@baylibre.com> References: <20240702-cleanup-ad7606-v3-1-18d5ea18770e@baylibre.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2024-07-02 at 12:52 +0000, Guillaume Stols wrote: > The current implementation attempts to recover from an eventual glitch > in the clock by checking frstdata state after reading the first > channel's sample: If frstdata is low, it will reset the chip and > return -EIO. >=20 > This will only work in parallel mode, where frstdata pin is set low > after the 2nd sample read starts. >=20 > For the serial mode, according to the datasheet, "The FRSTDATA output > returns to a logic low following the 16th SCLK falling edge.", thus > after the Xth pulse, X being the number of bits in a sample, the check > will always be true, and the driver will not work at all in serial > mode if frstdata(optional) is defined in the devicetree as it will > reset the chip, and return -EIO every time read_sample is called. >=20 > Hence, this check must be removed for serial mode. >=20 > Fixes: b9618c0cacd7 ("staging: IIO: ADC: New driver for AD7606/AD7606- > 6/AD7606-4") >=20 > Signed-off-by: Guillaume Stols > --- Reviewed-by: Nuno Sa