Patch "iio: trigger: stm32-timer: preset shouldn't be buffered" has been added to the 4.13-stable tree

Patch "iio: trigger: stm32-timer: preset shouldn't be buffered" has been added to the 4.13-stable tree

[gregkh]

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

    iio: trigger: stm32-timer: preset shouldn't be buffered

to the 4.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     iio-trigger-stm32-timer-preset-shouldn-t-be-buffered.patch
and it can be found in the queue-4.13 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 0a56eabc4e3f730782e4a9f3af4f60aa03a8a849 Mon Sep 17 00:00:00 2001
From: Fabrice Gasnier <fabrice.gasnier@st.com>
Date: Mon, 18 Sep 2017 12:05:30 +0200
Subject: iio: trigger: stm32-timer: preset shouldn't be buffered

From: Fabrice Gasnier <fabrice.gasnier@st.com>

commit 0a56eabc4e3f730782e4a9f3af4f60aa03a8a849 upstream.

Currently, setting preset value (ARR) will update directly 'Auto reload
value' only on 1st write access. But then, ARPE is set. This makes
ARR a shadow register. Preset value should be updated upon each
write request: ensure ARPE is 0. This fixes successive writes to
preset attribute.

Fixes: 4adec7da0536 ("iio: stm32 trigger: Add quadrature encoder device")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/iio/trigger/stm32-timer-trigger.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/iio/trigger/stm32-timer-trigger.c
+++ b/drivers/iio/trigger/stm32-timer-trigger.c
@@ -679,8 +679,9 @@ static ssize_t stm32_count_set_preset(st
 	if (ret)
 		return ret;
 
+	/* TIMx_ARR register shouldn't be buffered (ARPE=0) */
+	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, 0);
 	regmap_write(priv->regmap, TIM_ARR, preset);
-	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
 
 	return len;
 }


Patches currently in stable-queue which might be from fabrice.gasnier@st.com are

queue-4.13/iio-adc-stm32-fix-bad-error-check-on-max_channels.patch
queue-4.13/iio-trigger-stm32-timer-preset-shouldn-t-be-buffered.patch
queue-4.13/iio-trigger-stm32-timer-fix-a-corner-case-to-write-preset.patch