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

iio: adc: stm32: fix scan of multiple channels with DMA

to the 4.14-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-adc-stm32-fix-scan-of-multiple-channels-with-dma.patch and it can be found in the queue-4.14 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 04e491ca9df60ffe8637d00d68e5ab8bc73b30d5 Mon Sep 17 00:00:00 2001

From: Fabrice Gasnier fabrice.gasnier@st.com Date: Fri, 5 Jan 2018 15:34:54 +0100 Subject: iio: adc: stm32: fix scan of multiple channels with DMA

From: Fabrice Gasnier fabrice.gasnier@st.com

commit 04e491ca9df60ffe8637d00d68e5ab8bc73b30d5 upstream.

By default, watermark is set to '1'. Watermark is used to fine tune cyclic dma buffer period. In case watermark is left untouched (e.g. 1) and several channels are being scanned, buffer period is wrongly set (e.g. to 1 sample). As a consequence, data is never pushed to upper layer. Fix buffer period size, by taking scan channels number into account.

Fixes: 2763ea0585c9 ("iio: adc: stm32: add optional dma support")

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/adc/stm32-adc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/iio/adc/stm32-adc.c +++ b/drivers/iio/adc/stm32-adc.c @@ -1314,6 +1314,7 @@ static int stm32_adc_set_watermark(struc { struct stm32_adc *adc = iio_priv(indio_dev); unsigned int watermark = STM32_DMA_BUFFER_SIZE / 2; + unsigned int rx_buf_sz = STM32_DMA_BUFFER_SIZE;

/* * dma cyclic transfers are used, buffer is split into two periods. @@ -1322,7 +1323,7 @@ static int stm32_adc_set_watermark(struc * - one buffer (period) driver can push with iio_trigger_poll(). */ watermark = min(watermark, val * (unsigned)(sizeof(u16))); - adc->rx_buf_sz = watermark * 2; + adc->rx_buf_sz = min(rx_buf_sz, watermark * 2 * adc->num_conv);

return 0; }

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

queue-4.14/iio-adc-stm32-fix-scan-of-multiple-channels-with-dma.patch