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Wed, 14 Jan 2026 04:28:23 -0800 (PST) Message-ID: <34e97dbb610e82953657d8354c0a343a9e1fa57a.camel@gmail.com> Subject: Re: [PATCH v3 4/4] iio: adc: ad9467: check for backend capabilities From: Nuno =?ISO-8859-1?Q?S=E1?= To: Tomas Melin , Michael Hennerich , Nuno Sa , Lars-Peter Clausen , Jonathan Cameron , David Lechner , Andy Shevchenko , Olivier Moysan Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 14 Jan 2026 12:29:06 +0000 In-Reply-To: <20260114-b4-ad9467-optional-backend-v3-4-d2c84979d010@vaisala.com> References: <20260114-b4-ad9467-optional-backend-v3-0-d2c84979d010@vaisala.com> <20260114-b4-ad9467-optional-backend-v3-4-d2c84979d010@vaisala.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2026-01-14 at 10:45 +0000, Tomas Melin wrote: > Add capability checks for operation with backends that do not support > full set of features, but are otherwise compatible with the device. >=20 > Signed-off-by: Tomas Melin > --- > =C2=A0drivers/iio/adc/ad9467.c | 11 ++++++++++- > =C2=A01 file changed, 10 insertions(+), 1 deletion(-) >=20 > diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c > index 9cfe66425d4e91e215cccc40e24a92c5e99e9b87..349779a049ad68b4c9f72abfc= 40154b4a3f2e095 100644 > --- a/drivers/iio/adc/ad9467.c > +++ b/drivers/iio/adc/ad9467.c > @@ -645,6 +645,9 @@ static int ad9467_backend_testmode_on(struct ad9467_s= tate *st, > =C2=A0 }; > =C2=A0 int ret; > =C2=A0 > + if (!iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION)) > + return 0; > + > =C2=A0 ret =3D iio_backend_data_format_set(st->back, chan, &data); > =C2=A0 if (ret) > =C2=A0 return ret; > @@ -665,6 +668,9 @@ static int ad9467_backend_testmode_off(struct ad9467_= state *st, > =C2=A0 }; > =C2=A0 int ret; > =C2=A0 > + if (!iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION)) > + return 0; > + > =C2=A0 ret =3D iio_backend_chan_disable(st->back, chan); > =C2=A0 if (ret) > =C2=A0 return ret; > @@ -807,6 +813,9 @@ static int ad9467_calibrate(struct ad9467_state *st) > =C2=A0 bool invert =3D false, stat; > =C2=A0 int ret; > =C2=A0 > + if (!iio_backend_has_caps(st->back, IIO_BACKEND_CAP_CALIBRATION)) > + return 0; > + As David suggested, it might make more sense to do the check from the calle= rs. Not as important as within the backend functions though. > =C2=A0 /* all points invalid */ > =C2=A0 bitmap_fill(st->calib_map, st->calib_map_size); > =C2=A0 > @@ -1357,7 +1366,7 @@ static int ad9467_probe(struct spi_device *spi) > =C2=A0 return ret; > =C2=A0 > =C2=A0 ret =3D devm_iio_backend_request_buffer(&spi->dev, st->back, indio= _dev); > - if (ret) > + if (ret && ret !=3D -EOPNOTSUPP) > =C2=A0 return ret; Don't agree with the above. I would prefer to see a dedicated CAP for buffe= ring otherwise I would argue why not doing the same for everything? While it mig= ht be acceptable merging IIO_BACKEND_CAP_TEST_PATTERNS and IIO_BACKEND_CAP_CAL= IBRATION (given they are related to some extent), that does not apply to buffering. - Nuno S=C3=A1