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([2001:818:ea8e:7f00:2575:914:eedd:620e]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a099ae3cfbsm1349079f8f.40.2025.05.02.00.43.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 May 2025 00:43:49 -0700 (PDT) Message-ID: <29d79f863bd0352fa0e3fca36ba5cc007f467eff.camel@gmail.com> Subject: Re: [PATCH 3/5] iio: adc: ad7606: add offset and phase calibration support From: Nuno =?ISO-8859-1?Q?S=E1?= To: David Lechner , Angelo Dureghello , Jonathan Cameron , Nuno =?ISO-8859-1?Q?S=E1?= , Andy Shevchenko , Lars-Peter Clausen , Michael Hennerich , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Date: Fri, 02 May 2025 08:43:55 +0100 In-Reply-To: References: <20250429-wip-bl-ad7606-calibration-v1-0-eb4d4821b172@baylibre.com> <20250429-wip-bl-ad7606-calibration-v1-3-eb4d4821b172@baylibre.com> <9c02b2bd-dabf-4818-8adf-83c9127946d1@baylibre.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.1 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-04-30 at 13:33 -0500, David Lechner wrote: > On 4/30/25 11:14 AM, David Lechner wrote: > > On 4/30/25 10:36 AM, Nuno S=C3=A1 wrote: > > > On Tue, 2025-04-29 at 15:06 +0200, Angelo Dureghello wrote: > > > > From: Angelo Dureghello > > > >=20 > > > >=20 >=20 > ... >=20 > > > > + > > > > + val +=3D start_val; > > >=20 > > > Shouldn't this be val -=3D start_val? > > >=20 > > > I also don't think we have any strict rules in the ABI for units for = these > > > kind > > > of interfaces so using "raw" values is easier. But FWIW, I think we c= ould > > > have > > > this in mv (would naturally depend on scale)=20 > > >=20 > > > - Nuno S=C3=A1 > > >=20 > >=20 > > From testing, it seems to be working as expected for me, so I think thi= s is > > correct. The register value is not signed. 0x80 is no offset. > >=20 >=20 > Heh, you are actually quite right. Even though it working correctly, it i= s > because the value that gets written to the register is val & 0xFF, so add= ing > or subtracting here basically has the same effect. But subtracting is the= more > logical way to do it. (I tested it that way too just to be 100% sure.) Yeps, when testing it i realized that the current form just gives the corre= ct value in the 2 LSB so I assumed we were doing something to cast way the inv= alid bits. To be more pedantic, I think subtracting is the *correct* way :) - Nuno S=C3=A1