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AJvYcCUtiYh9HjYh+Ld/aw0MafsYQgyBL6+qUJH/zrZXh+BTz84rOXaGaLSRHq2h7wXMshJwiyzZET8l7aSz@vger.kernel.org X-Gm-Message-State: AOJu0Yxffn1FlqRiLQF+cFIu2fMVRtouRVyAEuNgK/Wo+EDPoOJo5wDr oFQn+wRrDe8K2v4p9yWLZaqY5tQZ76Ff6xy4fAo7e/vShXJG77KAprmp2xcbhgbl+O50d0YBPWE 6tl30TTgib+BGOj+MyZ9NvRKTOTqZTgMahNHRig== X-Google-Smtp-Source: AGHT+IE3wc+LCKuHli2wuMbRdahOui7PqfSTzFfrH+tmjl9a3NTlUglV7xXSsSlrCqlm17xHnQ5uDRj+5ZkjFmjANCc= X-Received: by 2002:a05:6122:169e:b0:50d:8d89:9f4 with SMTP id 71dfb90a1353d-50fb2707490mr2701901e0c.3.1729577395133; Mon, 21 Oct 2024 23:09:55 -0700 (PDT) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20241021130221.1469099-1-aardelean@baylibre.com> <20241021130221.1469099-4-aardelean@baylibre.com> In-Reply-To: From: Alexandru Ardelean Date: Tue, 22 Oct 2024 09:09:45 +0300 Message-ID: Subject: Re: [PATCH 3/6] iio: adc: ad7606: use realbits for sign-extending in scan_direct To: David Lechner Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, jic23@kernel.org, krzk+dt@kernel.org, robh@kernel.org, lars@metafoo.de, michael.hennerich@analog.com, gstols@baylibre.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Oct 21, 2024 at 8:19=E2=80=AFPM David Lechner wrote: > > On 10/21/24 8:02 AM, Alexandru Ardelean wrote: > > Currently the 'ad7606' driver supports parts with 18 and 16 bits > > resolutions. > > But when adding support for AD7607 (which has a 14-bit resolution) we > > should check for the 'realbits' field, to be able to sign-extend correc= tly. > > > > Signed-off-by: Alexandru Ardelean > > --- > > drivers/iio/adc/ad7606.c | 24 +++++++++++++++++++----- > > 1 file changed, 19 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c > > index d0fe9fd65f3f..a1f0c2feb04a 100644 > > --- a/drivers/iio/adc/ad7606.c > > +++ b/drivers/iio/adc/ad7606.c > > @@ -568,7 +568,7 @@ static int ad7606_scan_direct(struct iio_dev *indio= _dev, unsigned int ch, > > int *val) > > { > > struct ad7606_state *st =3D iio_priv(indio_dev); > > - unsigned int storagebits =3D st->chip_info->channels[1].scan_type= .storagebits; > > + unsigned int realbits =3D st->chip_info->channels[1].scan_type.re= albits; > > const struct iio_chan_spec *chan; > > int ret; > > > > @@ -603,15 +603,29 @@ static int ad7606_scan_direct(struct iio_dev *ind= io_dev, unsigned int ch, > > > > chan =3D &indio_dev->channels[ch + 1]; > > if (chan->scan_type.sign =3D=3D 'u') { > > - if (storagebits > 16) > > I think it would be simpler to keep this if statement for choosing > which data.bufXX to use since there are only 2 choices. > > > > + switch (realbits) { > > + case 18: > > *val =3D st->data.buf32[ch]; > > - else > > + break; > > + case 16: > > *val =3D st->data.buf16[ch]; > > + break; > > + default: > > + ret =3D -EINVAL; > > + break; > > + } > > } else { > > - if (storagebits > 16) > > + switch (realbits) { > > + case 18: > > *val =3D sign_extend32(st->data.buf32[ch], 17); > > - else > > + break; > > + case 16: > > *val =3D sign_extend32(st->data.buf16[ch], 15); > > + break; > > + default: > > + ret =3D -EINVAL; > > + break; > > + } > > We can change this to: > > *val =3D sign_extend32(st->data.buf16[ch], reablbits - 1); > > Then no additional changes should be needed to support 14-bit chips. > > And similarly, we could avoid the need to use the more verbose > switch statement. Ack. > > > } > > > > error_ret: > >