This is a note to let you know that I've just added the patch titled
iio: hi8435: avoid garbage event at first enable
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: iio-hi8435-avoid-garbage-event-at-first-enable.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Tue Apr 10 10:31:53 CEST 2018
From: Nikita Yushchenko nikita.yoush@cogentembedded.com Date: Fri, 19 May 2017 17:48:00 +0300 Subject: iio: hi8435: avoid garbage event at first enable
From: Nikita Yushchenko nikita.yoush@cogentembedded.com
[ Upstream commit ee19ac340c5fdfd89c6348be4563453c61ab54a9 ]
Currently, driver generates events for channels if new reading differs from previous one. This "previous value" is initialized to zero, which results into event if value is constant-one.
Fix that by initializing "previous value" by reading at event enable time.
This provides reliable sequence for userspace: - enable event, - AFTER THAT read current value, - AFTER THAT each event will correspond to change.
Signed-off-by: Nikita Yushchenko nikita.yoush@cogentembedded.com Signed-off-by: Jonathan Cameron jic23@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iio/adc/hi8435.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)
--- a/drivers/iio/adc/hi8435.c +++ b/drivers/iio/adc/hi8435.c @@ -121,10 +121,21 @@ static int hi8435_write_event_config(str enum iio_event_direction dir, int state) { struct hi8435_priv *priv = iio_priv(idev); + int ret; + u32 tmp; + + if (state) { + ret = hi8435_readl(priv, HI8435_SO31_0_REG, &tmp); + if (ret < 0) + return ret; + if (tmp & BIT(chan->channel)) + priv->event_prev_val |= BIT(chan->channel); + else + priv->event_prev_val &= ~BIT(chan->channel);
- priv->event_scan_mask &= ~BIT(chan->channel); - if (state) priv->event_scan_mask |= BIT(chan->channel); + } else + priv->event_scan_mask &= ~BIT(chan->channel);
return 0; }
Patches currently in stable-queue which might be from nikita.yoush@cogentembedded.com are
queue-4.4/iio-hi8435-avoid-garbage-event-at-first-enable.patch queue-4.4/iio-hi8435-cleanup-reset-gpio.patch