From cae8339cac4738f930d8e513f4c781e25b33c772 Mon Sep 17 00:00:00 2001 From: Fabrice Gasnier Date: Fri, 5 Jan 2018 15:34:54 +0100 Subject: [PATCH] iio: adc: stm32: fix scan of multiple channels with DMA 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: 7b68baad3a96 ("iio: adc: stm32: add optional dma support") Signed-off-by: Fabrice Gasnier Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/adc/stm32-adc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c index 6dbf9549cdc9b..7f5def465340e 100644 --- a/drivers/iio/adc/stm32-adc.c +++ b/drivers/iio/adc/stm32-adc.c @@ -1289,6 +1289,7 @@ 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. @@ -1297,7 +1298,7 @@ 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; } -- 2.39.5