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Sun, 19 Jul 2026 16:42:22 -0700 (PDT) X-Received: by 2002:a05:6a00:194d:b0:848:559f:1450 with SMTP id d2e1a72fcca58-84c295835c9mr11828535b3a.74.1784504541722; Sun, 19 Jul 2026 16:42:21 -0700 (PDT) Received: from jic23-huawei ([50.35.46.84]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84c2adfdfe9sm4617809b3a.27.2026.07.19.16.42.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Jul 2026 16:42:21 -0700 (PDT) Date: Mon, 20 Jul 2026 00:42:18 +0100 From: Jonathan Cameron To: "David Lechner (TI)" Cc: Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Chris Hall , Patrick Edwards , Kurt Borja , Nguyen Minh Tien , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 6/8] iio: adc: add ti-ads112c14 driver Message-ID: <20260720004218.4e010404@jic23-huawei> In-Reply-To: <20260720000805.41022604@jic23-huawei> References: <20260714-iio-adc-ti-ads122c14-v4-0-25f8e3084485@baylibre.com> <20260714-iio-adc-ti-ads122c14-v4-6-25f8e3084485@baylibre.com> <20260720000805.41022604@jic23-huawei> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=HpxG3UTS c=1 sm=1 tr=0 ts=6a5d60de cx=c_pps a=mDZGXZTwRPZaeRUbqKGCBw==:117 a=qC1CW/w66vtJz1P9yTJxNA==:17 a=kj9zAlcOel0A:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=Um2Pa8k9VHT-vaBCBUpS:22 a=EUspDBNiAAAA:8 a=IpJZQVW2AAAA:8 a=wGoPyE8iD8i8cuqfmxkA:9 a=CjuIK1q_8ugA:10 a=zc0IvFSfCIW2DFIPzwfm:22 a=IawgGOuG5U0WyFbmm1f5:22 X-Proofpoint-GUID: xx6c6Qn7JrotOREs6KqVhAfoE0vH2oZz X-Proofpoint-ORIG-GUID: xx6c6Qn7JrotOREs6KqVhAfoE0vH2oZz X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE5MDI2NiBTYWx0ZWRfX8T2DrIVhIaAH PnT841Ss1FjPAnKjge0K3PyBX2ivGB+qgy8dN3tALyR1sK2VLUAOyV5QzxG+UgsKfUHBsaxMfyh 0+nMw4JlxdFZ80Zegi8F53SM258jrgbPgr1jirGdylc8iCNK6QOuw+tcpqBWf/GjmfOQQy+awl+ 9amK0INfNdF2u3FLkAi/2ATToT4uhcEHv3gVRVGpPWtQfWOaz4XDppXIgMTNVau6vBd52jQmmD6 qlVYoM+KrxO28S4QI6/UDvLKaC18n2soLkFEKXdLOTj43ObAO5EtV1UzGjAcxeIyyLi5GjpM6hU yIhfrQs6sqNugPM48objG0ge6cuf5R4hzY4+qZZ34chcobotbxpVWugr3P8s0I8kgWkAy9DS2aH 1l43zD/Tk3BF/frPKynbxt8bEM52nLvEKhC1gO5JVoDDNfSgpkUhFXbXvoIho+BbVp9TuCnVdpn 0qNSOtNTGymrKpw9TsA== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzE5MDI2NiBTYWx0ZWRfX85L1XsOwFV91 t5szbTR1WlGDiRLR529d1qAdSki1JpwAUnjAAOYh351lR0Pd+GAXsD3ZCwaZj2Jm7HdL5Wrw+8C gW0mKV7ENii5y0IZYyLXXag1KnK3CM4= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-19_07,2026-07-17_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 impostorscore=0 malwarescore=0 clxscore=1015 priorityscore=1501 adultscore=0 spamscore=0 suspectscore=0 lowpriorityscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607190266 On Mon, 20 Jul 2026 00:08:05 +0100 Jonathan Cameron wrote: > On Tue, 14 Jul 2026 18:21:28 -0500 > "David Lechner (TI)" wrote: > > > Add a new driver for the TI ADS112C14/ADS122C14 ADC chips. > > > > This first step is adding a very basic driver that only supports power > > on/reset and reading the system monitor channels. > > > > ADS112C14_SYS_MON_CHANNEL_SHORT is the last channel rather than being in > > logical order by address to keep the voltage channels together and in > > case we find we need to add variants of this channel with different > > voltage reference later. > > > > Signed-off-by: David Lechner (TI) > I think sashiko is sending us on a wild goose chase on this one. > > "When ads112c14_single_conversion() calls i2c_smbus_read_i2c_block_data(), it > returns the number of bytes read upon success. A short read (e.g. 1 or 2 bytes) > would return a positive value, bypassing the (ret < 0) error check in > ads112c14_read_raw()." > > An i2c_smbus_read_i2c_block_data() response doesn't contain a length > unlike i2c_smbus_read_block_data() which does. > > Maybe there is a controller driver out there that messes with block[0] > rather than returning an error on failure to do the read part of > the sequence. I checked a few and didn't find one. > > It might make sense to make it clear this doesn't happen by > adding checks in the i2c core. One to consider after the other > ones on my list! > > However, one small related comment inline about keeping postive > return values meaning success as local as possible in the code! > I'm having a perhaps optimistic go at tweaking this to resolve remaining tiny issues and avoid need for a v5. Tweak here is: diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c index a69c595ab518..bc0fd6839b72 100644 --- a/drivers/iio/adc/ti-ads112c14.c +++ b/drivers/iio/adc/ti-ads112c14.c @@ -322,9 +322,13 @@ static int ads112c14_single_conversion(struct ads112c14_data *data, if (ret) return ret; - return i2c_smbus_read_i2c_block_data(client, ADS112C14_CMD_RDATA, - BITS_TO_BYTES(data->chip_info->resolution_bits), - buf); + ret = i2c_smbus_read_i2c_block_data(client, ADS112C14_CMD_RDATA, + BITS_TO_BYTES(data->chip_info->resolution_bits), + buf); + if (ret < 0) + return ret; + + return 0; } static int ads112c14_read_raw(struct iio_dev *indio_dev, @@ -355,7 +359,7 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev, return -EBUSY; ret = ads112c14_single_conversion(data, chan, buf); - if (ret < 0) + if (ret) return ret; switch (data->chip_info->resolution_bits) { > Jonathan > > > > > > diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c > > new file mode 100644 > > index 000000000000..a69c595ab518 > > --- /dev/null > > +++ b/drivers/iio/adc/ti-ads112c14.c > > ... > > > + > > +static int ads112c14_single_conversion(struct ads112c14_data *data, > > + const struct iio_chan_spec *chan, > > + u8 *buf) > > +{ > > + struct i2c_client *client = to_i2c_client(regmap_get_device(data->regmap)); > > + u32 reg_val; > > + int ret; > > + > > + if (chan->channel < ADS112C14_SYS_MON_CHANNEL_BASE) { > > + /* Not implemented yet. */ > > + return -EINVAL; > > + } else { > > + ret = ads112c14_prepare_sys_mon_channel(data, chan); > > + if (ret) > > + return ret; > > + } > > + > > + ret = regmap_write(data->regmap, ADS112C14_REG_CONVERSION_CTRL, > > + ADS112C14_CONVERSION_CTRL_START); > > + if (ret) > > + return ret; > > + > > + ret = regmap_read_poll_timeout(data->regmap, > > + ADS112C14_REG_STATUS_MSB, reg_val, > > + FIELD_GET(ADS112C14_STATUS_MSB_DRDY, reg_val), > > + 1 * USEC_PER_MSEC, 100 * USEC_PER_MSEC); > > + if (ret) > > + return ret; > > + > > + return i2c_smbus_read_i2c_block_data(client, ADS112C14_CMD_RDATA, > > + BITS_TO_BYTES(data->chip_info->resolution_bits), > > + buf); > With all that stuff above about this not returning short, I'd still be tempted to do > an if (ret < 0) return ret; return 0; sequence in here so we don't propogate > confusing positive returns beyond where we can see their source. > > Having done that make the outer check if (ret) > > > > +} >