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Date: Mon, 15 Jan 2024 11:12:17 +0100
From: Mårten Lindahl <martenli@...s.com>
To: Jonathan Cameron <jic23@...nel.org>,
Mårten Lindahl <marten.lindahl@...s.com>
Cc: Lars-Peter Clausen <lars@...afoo.de>, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org, kernel@...s.com
Subject: Re: [PATCH v2] iio: light: vcnl4000: Set ps high definition for
4040/4200
On 1/13/24 16:07, Jonathan Cameron wrote:
> On Wed, 10 Jan 2024 13:58:07 +0100
> Mårten Lindahl <marten.lindahl@...s.com> wrote:
>
>> The vcnl4040/vcnl4200 proximity sensor defaults to 12 bit data
>> resolution, but the chip also supports 16 bit data resolution, which is
>> called proximity high definition (PS_HD).
>>
>> Make the vcnl4040/vcnl4200 proximity sensor use the high definition for
>> all data readings. Please note that in order to preserve the 12 bit
>> integer part of the in_proximity_raw output, the format is changed from
>> integer to fixed point.
>>
>> Signed-off-by: Mårten Lindahl <marten.lindahl@...s.com>
> Hi Mårten,
>
> I don't understand why we'd try to carry on with using the device if
> the additional register accesses fail. Just fail the probe, the hardware
> is broken.
>
> Jonathan
Hi Jonathan!
Fair point. I'll fail the probe if the register accesses fail. It's
unlikely that the device would work if these fail.
Kind regards
Mårten
>
>> ---
>> Changes in v2:
>> - Update registers for sample rate to align it with 16 bit sensor readings.
>> - Change sysfs output from IIO_VAL_INT to IIO_VAL_FRACTIONAL and scale by 16.
>> - Link to v1: https://lore.kernel.org/r/20231221-vcnl4000-ps-hd-v1-1-a024bfb28896@axis.com
>> ---
>> drivers/iio/light/vcnl4000.c | 40 +++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 39 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iio/light/vcnl4000.c b/drivers/iio/light/vcnl4000.c
>> index fdf763a04b0b..a078c573131e 100644
>> --- a/drivers/iio/light/vcnl4000.c
>> +++ b/drivers/iio/light/vcnl4000.c
>> @@ -90,6 +90,7 @@
>> #define VCNL4040_PS_CONF1_PS_SHUTDOWN BIT(0)
>> #define VCNL4040_PS_CONF2_PS_IT GENMASK(3, 1) /* Proximity integration time */
>> #define VCNL4040_CONF1_PS_PERS GENMASK(5, 4) /* Proximity interrupt persistence setting */
>> +#define VCNL4040_PS_CONF2_PS_HD BIT(11) /* Proximity high definition */
>> #define VCNL4040_PS_CONF2_PS_INT GENMASK(9, 8) /* Proximity interrupt mode */
>> #define VCNL4040_PS_CONF3_MPS GENMASK(6, 5) /* Proximity multi pulse number */
>> #define VCNL4040_PS_MS_LED_I GENMASK(10, 8) /* Proximity current */
>> @@ -114,6 +115,13 @@
>> #define VCNL4010_INT_DRDY \
>> (BIT(VCNL4010_INT_PROXIMITY) | BIT(VCNL4010_INT_ALS))
>>
>> +#define VCNL4040_CONF3_PS_MPS_16BITS 3 /* 8 multi pulses */
>> +#define VCNL4040_CONF3_PS_LED_I_16BITS 3 /* 120 mA */
>> +
>> +#define VCNL4040_CONF3_PS_SAMPLE_16BITS \
>> + (FIELD_PREP(VCNL4040_PS_CONF3_MPS, VCNL4040_CONF3_PS_MPS_16BITS) | \
>> + FIELD_PREP(VCNL4040_PS_MS_LED_I, VCNL4040_CONF3_PS_LED_I_16BITS))
>> +
>> static const int vcnl4010_prox_sampling_frequency[][2] = {
>> {1, 950000},
>> {3, 906250},
>> @@ -195,6 +203,7 @@ struct vcnl4000_data {
>> enum vcnl4000_device_ids id;
>> int rev;
>> int al_scale;
>> + int ps_scale;
>> u8 ps_int; /* proximity interrupt mode */
>> u8 als_int; /* ambient light interrupt mode*/
>> const struct vcnl4000_chip_spec *chip_spec;
>> @@ -345,6 +354,7 @@ static int vcnl4200_set_power_state(struct vcnl4000_data *data, bool on)
>> static int vcnl4200_init(struct vcnl4000_data *data)
>> {
>> int ret, id;
>> + u16 regval;
>>
>> ret = i2c_smbus_read_word_data(data->client, VCNL4200_DEV_ID);
>> if (ret < 0)
>> @@ -386,9 +396,36 @@ static int vcnl4200_init(struct vcnl4000_data *data)
>> break;
>> }
>> data->al_scale = data->chip_spec->ulux_step;
>> + data->ps_scale = 16;
>> mutex_init(&data->vcnl4200_al.lock);
>> mutex_init(&data->vcnl4200_ps.lock);
>>
>> + /* Use 16 bits proximity sensor readings */
>> + ret = i2c_smbus_read_word_data(data->client, VCNL4200_PS_CONF1);
>> + if (ret >= 0) {
>> + regval = (ret | VCNL4040_PS_CONF2_PS_HD);
> Trivial but those brackets are unnecessary.
>
>> + ret = i2c_smbus_write_word_data(data->client, VCNL4200_PS_CONF1,
>> + regval);
>> + }
>> +
>> + if (ret < 0) {
>> + dev_info(&data->client->dev, "Default to 12 bits sensor data");
> Silly question - how can we get here? If it's a case of a read or a write failing
> then that's a critical failure and we have very little idea what the state is.
> If that happens I'd just fail to probe the driver rather than carrying on with
> 12 bit assumed.
>
>> + data->ps_scale = 1;
>> + goto out;
>> + }
>> +
>> + /* Align proximity sensor sample rate to 16 bits data width */
>> + ret = i2c_smbus_read_word_data(data->client, VCNL4200_PS_CONF3);
>> + if (ret >= 0) {
> If the read fails, something is very wrong. Fail the probe.
>
>> + regval = (ret | VCNL4040_CONF3_PS_SAMPLE_16BITS);
>> + ret = i2c_smbus_write_word_data(data->client, VCNL4200_PS_CONF3,
>> + regval);
>> + }
>> +
>> + if (ret < 0)
>> + dev_warn(&data->client->dev, "Sample rate may not be accurate");
> If this fails, fail the probe. Don't try to carry on anyway.
>
>
>> +
>> +out:
>> ret = data->chip_spec->set_power_state(data, true);
>> if (ret < 0)
>> return ret;
>> @@ -901,8 +938,9 @@ static int vcnl4000_read_raw(struct iio_dev *indio_dev,
>> break;
>> case IIO_PROXIMITY:
>> ret = data->chip_spec->measure_proximity(data, val);
>> + *val2 = data->ps_scale;
>> if (!ret)
>> - ret = IIO_VAL_INT;
>> + ret = IIO_VAL_FRACTIONAL;
>> break;
>> default:
>> ret = -EINVAL;
>>
>> ---
>> base-commit: a39b6ac3781d46ba18193c9dbb2110f31e9bffe9
>> change-id: 20231221-vcnl4000-ps-hd-863f4f8fcea7
>>
>> Best regards,
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