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([2001:a61:35f9:9001:40df:88bb:5090:7ab6]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-57d3042d10csm4880811a12.40.2024.06.24.08.22.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jun 2024 08:22:54 -0700 (PDT) Message-ID: <1ef85cdcffefee6b6a68927816f3d26c074a5331.camel@gmail.com> Subject: Re: [PATCH 7/8] iio: add sd modulator generic iio backend From: Nuno =?ISO-8859-1?Q?S=E1?= To: Olivier MOYSAN , Jonathan Cameron Cc: Lars-Peter Clausen , Liam Girdwood , Mark Brown , linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org Date: Mon, 24 Jun 2024 17:22:54 +0200 In-Reply-To: <2dbd160b-135e-4882-9fd3-9d921742f49d@foss.st.com> References: <20240618160836.945242-1-olivier.moysan@foss.st.com> <20240618160836.945242-8-olivier.moysan@foss.st.com> <20240623161150.358f95bf@jic23-huawei> <2dbd160b-135e-4882-9fd3-9d921742f49d@foss.st.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.2 (3.52.2-1.fc40) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hi Olivier, On Mon, 2024-06-24 at 14:43 +0200, Olivier MOYSAN wrote: > Hi Jonathan, >=20 > On 6/23/24 17:11, Jonathan Cameron wrote: > > On Tue, 18 Jun 2024 18:08:33 +0200 > > Olivier Moysan wrote: > >=20 > > > Add a generic driver to support sigma delta modulators. > > > Typically, this device is a hardware connected to an IIO device > > > in charge of the conversion. The device is exposed as an IIO backend > > > device. This backend device and the associated conversion device > > > can be seen as an aggregate device from IIO framework. > > >=20 > > > Signed-off-by: Olivier Moysan > >=20 > > Trivial comments inline. > >=20 > > > diff --git a/drivers/iio/adc/sd_adc_backend.c > > > b/drivers/iio/adc/sd_adc_backend.c > > > new file mode 100644 > > > index 000000000000..556a49dc537b > > > --- /dev/null > > > +++ b/drivers/iio/adc/sd_adc_backend.c > > > @@ -0,0 +1,110 @@ > > > +// SPDX-License-Identifier: GPL-2.0-only > > > +/* > > > + * Generic sigma delta modulator IIO backend > > > + * > > > + * Copyright (C) 2024, STMicroelectronics - All Rights Reserved > > > + */ > > > + > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > + > > > +struct iio_sd_backend_priv { > > > + struct regulator *vref; > > > + int vref_mv; > > > +}; > > > + > > > +static int sd_backend_enable(struct iio_backend *backend) > > > +{ > > > + struct iio_sd_backend_priv *priv =3D iio_backend_get_priv(backend); > > > + > > > + return regulator_enable(priv->vref); > > > +}; > > > + > > > +static void sd_backend_disable(struct iio_backend *backend) > > > +{ > > > + struct iio_sd_backend_priv *priv =3D iio_backend_get_priv(backend); > > > + > > > + regulator_disable(priv->vref); > > > +}; > > > + > > > +static int sd_backend_read(struct iio_backend *backend, int *val, in= t *val2, > > > long mask) > > Nothing to do with this patch as such: > >=20 > > One day I'm going to bit the bullet and fix that naming. > > Long long ago when the Earth was young it actually was a bitmap which > > I miscalled a mask - it only had one bit ever set, which was a dumb > > bit of API.=C2=A0 It's not been true for a long time. > > Anyhow, one more instances isn't too much of a problem I guess. > >=20 >=20 > I changed the callback .read_raw to .ext_info_get to take Nuno's comment= =20 > about iio_backend_read_raw() API, into account. > So, I changed this function to > static int sd_backend_ext_info_get(struct iio_backend *back, uintptr_t= =20 > private, const struct iio_chan_spec *chan, char *buf) > for v2 version. >=20 Maybe I'm missing something but I think I did not explained myself very wel= l. What I had in mind was that since you're calling .read_raw() from IIO_CHAN_INFO_SC= ALE and IIO_CHAN_INFO_OFFSET, it could make sense to have more dedicated API's. Mea= ning: iio_backend_read_scale(...) iio_backend_read_offset(...) The iio_backend_read_raw() may make sense when frontends call iio_backend_extend_chan_spec() and have no idea what the backend may have a= dded to the channel. So, in those cases something like this could make sense: switch (mask) IIO_CHAN_INFO_RAW: ... default: return iio_backend_read_raw(); but like I said maybe this is me over-complicating and a simple iio_backend_read_raw() is sufficient. But I think I never mentioned somethi= ng like .read_raw -> .ext_info_get. The other thing I mentioned was to instead of having: if (child) { ch->info_mask_separate =3D BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET); } You could use iio_backend_extend_chan_spec() and have the backend set the S= CALE and OFFSET bits for you as it seems these functionality depends on the backend. But none of the above were critical or things that I feel to strong about. Anyways, just wanted to give some clarification as it seems there were some misunderstandings (I think). - Nuno S=C3=A1 > >=20