From: Jonathan Cameron <jic23@kernel.org>
To: "Matti Lehtimäki" <matti.lehtimaki@gmail.com>
Cc: linux-iio@vger.kernel.org, ~postmarketos/upstreaming@lists.sr.ht,
Lars-Peter Clausen <lars@metafoo.de>,
Miquel Raynal <miquel.raynal@bootlin.com>,
Linus Walleij <linus.walleij@linaro.org>,
Alexandru Ardelean <aardelean@deviqon.com>,
Cai Huoqing <cai.huoqing@linux.dev>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] iio: st_sensors: Retry ID verification on failure
Date: Sun, 31 Jul 2022 17:00:57 +0100 [thread overview]
Message-ID: <20220731170057.2b8ac00e@jic23-huawei> (raw)
In-Reply-To: <20220724164316.68393-1-matti.lehtimaki@gmail.com>
On Sun, 24 Jul 2022 19:43:15 +0300
Matti Lehtimäki <matti.lehtimaki@gmail.com> wrote:
> Some sensors do not always start fast enough to read a valid ID from
> registers at first attempt. Let's retry at most 3 times with short sleep
> in between to fix random timing issues.
>
> Signed-off-by: Matti Lehtimäki <matti.lehtimaki@gmail.com>
Hi Matti,
My gut feeling is this isn't in a fast path, so why not just wait
for whatever the documented power up time of the sensor is?
I'd expect to see a sleep in st_sensors_power_enable() if one is
required.
Jonathan
> ---
> drivers/iio/common/st_sensors/st_sensors_core.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c b/drivers/iio/common/st_sensors/st_sensors_core.c
> index 9910ba1da085..106f7953683e 100644
> --- a/drivers/iio/common/st_sensors/st_sensors_core.c
> +++ b/drivers/iio/common/st_sensors/st_sensors_core.c
> @@ -21,6 +21,8 @@
>
> #include "st_sensors_core.h"
>
> +#define VERIFY_ID_RETRY_COUNT 3
> +
> int st_sensors_write_data_with_mask(struct iio_dev *indio_dev,
> u8 reg_addr, u8 mask, u8 data)
> {
> @@ -619,11 +621,18 @@ EXPORT_SYMBOL_NS(st_sensors_get_settings_index, IIO_ST_SENSORS);
> int st_sensors_verify_id(struct iio_dev *indio_dev)
> {
> struct st_sensor_data *sdata = iio_priv(indio_dev);
> - int wai, err;
> + int wai, err, i;
>
> if (sdata->sensor_settings->wai_addr) {
> - err = regmap_read(sdata->regmap,
> - sdata->sensor_settings->wai_addr, &wai);
> + for (i = 0; i < VERIFY_ID_RETRY_COUNT; i++) {
> + err = regmap_read(sdata->regmap,
> + sdata->sensor_settings->wai_addr, &wai);
> +
> + if (!err && sdata->sensor_settings->wai == wai)
> + return 0;
> +
> + msleep(20);
How do we know 60msecs is long enough for all sensors?
> + }
> if (err < 0) {
> dev_err(&indio_dev->dev,
> "failed to read Who-Am-I register.\n");
next prev parent reply other threads:[~2022-07-31 15:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-24 16:43 [PATCH 1/2] iio: st_sensors: Retry ID verification on failure Matti Lehtimäki
2022-07-24 16:43 ` [PATCH 2/2] iio: st_sensors: Fix null pointer on defer_probe error Matti Lehtimäki
2022-07-25 21:24 ` Andy Shevchenko
2022-07-25 21:20 ` [PATCH 1/2] iio: st_sensors: Retry ID verification on failure Andy Shevchenko
2022-07-31 16:00 ` Jonathan Cameron [this message]
2022-07-31 18:51 ` Matti Lehtimäki
2022-07-31 20:17 ` Jonathan Cameron
2022-08-03 18:20 ` Linus Walleij
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