This is a note to let you know that I've just added the patch titled

iio: ltc2983: fix device probe

to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-testing branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will be merged to the staging-next branch sometime soon, after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.

From b76d26d69ecc97ebb24aaf40427a13c808a4f488 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Nuno=20S=C3=A1?= nuno.sa@analog.com Date: Wed, 11 Aug 2021 15:32:20 +0200 Subject: iio: ltc2983: fix device probe MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

There is no reason to assume that the IRQ rising edge (indicating that the device start up phase is done) will happen after we request the IRQ. If the device is already up by the time we request it, the call to 'wait_for_completion_timeout()' will timeout and we will fail the device probe even though there's nothing wrong.

Fix it by just polling the status register until we get the indication that the device is up and running. As a side effect of this fix, requesting the IRQ is also moved to after the setup function.

Fixes: f110f3188e563 ("iio: temperature: Add support for LTC2983") Reported-and-tested-by: Drew Fustini drew@pdp7.com Reviewed-by: Drew Fustini drew@pdp7.com Signed-off-by: Nuno Sá nuno.sa@analog.com Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Cc: Stable@vger.kernel.org Link: https://lore.kernel.org/r/20210811133220.190264-2-nuno.sa@analog.com Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com --- drivers/iio/temperature/ltc2983.c | 30 ++++++++++++++---------------- 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/iio/temperature/ltc2983.c b/drivers/iio/temperature/ltc2983.c index 3b5ba26d7d86..3b4a0e60e605 100644 --- a/drivers/iio/temperature/ltc2983.c +++ b/drivers/iio/temperature/ltc2983.c @@ -89,6 +89,8 @@

#define LTC2983_STATUS_START_MASK BIT(7) #define LTC2983_STATUS_START(x) FIELD_PREP(LTC2983_STATUS_START_MASK, x) +#define LTC2983_STATUS_UP_MASK GENMASK(7, 6) +#define LTC2983_STATUS_UP(reg) FIELD_GET(LTC2983_STATUS_UP_MASK, reg)

#define LTC2983_STATUS_CHAN_SEL_MASK GENMASK(4, 0) #define LTC2983_STATUS_CHAN_SEL(x) \ @@ -1362,17 +1364,16 @@ static int ltc2983_parse_dt(struct ltc2983_data *st)

static int ltc2983_setup(struct ltc2983_data *st, bool assign_iio) { - u32 iio_chan_t = 0, iio_chan_v = 0, chan, iio_idx = 0; + u32 iio_chan_t = 0, iio_chan_v = 0, chan, iio_idx = 0, status; int ret; - unsigned long time; - - /* make sure the device is up */ - time = wait_for_completion_timeout(&st->completion, - msecs_to_jiffies(250));

- if (!time) { + /* make sure the device is up: start bit (7) is 0 and done bit (6) is 1 */ + ret = regmap_read_poll_timeout(st->regmap, LTC2983_STATUS_REG, status, + LTC2983_STATUS_UP(status) == 1, 25000, + 25000 * 10); + if (ret) { dev_err(&st->spi->dev, "Device startup timed out\n"); - return -ETIMEDOUT; + return ret; }

st->iio_chan = devm_kzalloc(&st->spi->dev, @@ -1492,10 +1493,11 @@ static int ltc2983_probe(struct spi_device *spi) ret = ltc2983_parse_dt(st); if (ret) return ret; - /* - * let's request the irq now so it is used to sync the device - * startup in ltc2983_setup() - */ + + ret = ltc2983_setup(st, true); + if (ret) + return ret; + ret = devm_request_irq(&spi->dev, spi->irq, ltc2983_irq_handler, IRQF_TRIGGER_RISING, name, st); if (ret) { @@ -1503,10 +1505,6 @@ static int ltc2983_probe(struct spi_device *spi) return ret; }

- ret = ltc2983_setup(st, true); - if (ret) - return ret; - indio_dev->name = name; indio_dev->num_channels = st->iio_channels; indio_dev->channels = st->iio_chan;