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Commit e2d4cdb7 authored by Fabrice Gasnier's avatar Fabrice Gasnier Committed by Greg Kroah-Hartman
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iio: adc: stm32: fix scan of multiple channels with DMA 



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: 2763ea05 ("iio: adc: stm32: add optional dma support")

Signed-off-by: default avatarFabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cfd96cbd

drivers/iio/adc/stm32-adc.c

+2 −1
Original line number Diff line number Diff line
@@ -1314,6 +1314,7 @@ static int stm32_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val) 
{

	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(struct iio_dev *indio_dev, unsigned int val) 
	 * - 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;

}