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([2600:8803:e7e4:500:3533:aa22:9a69:df1c]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7e9ec2ba18esm461442a34.16.2026.06.29.11.55.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 29 Jun 2026 11:55:48 -0700 (PDT) Message-ID: <2cdb9cd4-8e6c-4bdf-b14e-2191b104d229@baylibre.com> Date: Mon, 29 Jun 2026 13:55:47 -0500 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/3] iio: adc: Fix incorrect reading when datarate changed in single mode To: Jonathan Cameron Cc: Jakub Szczudlo , linux-iio@vger.kernel.org, andy@kernel.org, antoniu.miclaus@analog.com, conor+dt@kernel.org, devicetree@vger.kernel.org, duje@dujemihanovic.xyz, jishnu.prakash@oss.qualcomm.com, jorge.marques@analog.com, joshua.crofts1@gmail.com, krzk+dt@kernel.org, linusw@kernel.org, linux-kernel@vger.kernel.org, marcelo.schmitt@analog.com, mazziesaccount@gmail.com, mike.looijmans@topic.nl, nuno.sa@analog.com, robh@kernel.org, sakari.ailus@linux.intel.com, wens@kernel.org References: <20260622221550.374235-1-jakubszczudlo40@gmail.com> <20260622221550.374235-2-jakubszczudlo40@gmail.com> <5e96801b-50dc-4752-8e00-1a80984ed997@baylibre.com> <20260629193329.34fab6e3@jic23-huawei> Content-Language: en-US From: David Lechner In-Reply-To: <20260629193329.34fab6e3@jic23-huawei> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/29/26 1:33 PM, Jonathan Cameron wrote: > On Sat, 27 Jun 2026 17:31:24 -0500 > David Lechner wrote: > >> On 6/22/26 5:15 PM, Jakub Szczudlo wrote: >>> When device is suspended and it is in single mode then changing >>> datarate doesn't make it actual wait for new measurement, so to >>> be sure that read after change is correct functions that changes >>> datarate and gain will wait for new data. >>> >>> Fixes: 541880542f2b ("iio: adc: Add TI ADS1100 and ADS1000") >>> Signed-off-by: Jakub Szczudlo >>> --- >>> drivers/iio/adc/ti-ads1100.c | 74 ++++++++++++++++++++++++++++++++++-- >>> 1 file changed, 70 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/iio/adc/ti-ads1100.c b/drivers/iio/adc/ti-ads1100.c >>> index 9fe8d54cce83..e3c801381434 100644 >>> --- a/drivers/iio/adc/ti-ads1100.c >>> +++ b/drivers/iio/adc/ti-ads1100.c >>> @@ -15,6 +15,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> #include >>> #include >>> #include >>> @@ -43,6 +44,9 @@ >>> static const int ads1100_data_rate[] = { 128, 32, 16, 8 }; >>> static const int ads1100_data_rate_bits[] = { 12, 14, 15, 16 }; >>> >>> +/* Timeout based on the minimum sample rate of 8 SPS (7.5s) */ >>> +#define ADS1100_MAX_DRDY_TIMEOUT_US 7500000 >>> + >>> struct ads1100_data { >>> struct i2c_client *client; >>> struct regulator *reg_vdd; >>> @@ -123,10 +127,49 @@ static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val) >>> return 0; >>> } >>> >>> +static bool ads1100_new_data_not_ready(struct ads1100_data *data) >>> +{ >>> + int ret; >>> + u8 buffer[3]; >>> + >>> + ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer)); >> >> Do we actually need the cast here? char * is like void * and should not need it. > Hi David, > > Any more background on this? The void * implicit cast thing is in the > c standard. I don't think there is anything equivalent for char * > > Thanks, > > Jonathan Oops, I must have been mixing that up with special type punning rules for char. According to [1], char is not compatible with either of signed char or unsigned char. [1]: https://en.cppreference.com/c/language/type#Compatible_types