From 1dbe7dada2d03d1313183d439068f1f951a91244 Mon Sep 17 00:00:00 2001 From: Alexander Stein Date: Thu, 5 May 2011 08:40:14 -0700 Subject: [PATCH] Input: ads7846 - make transfer buffers DMA safe req.sample needs its own cacheline otherwise accessing req.msg fetches it in again. Note: This effect doesn't occur if the underlying SPI driver doesn't use DMA at all. Signed-off-by: Alexander Stein Acked-by: Jonathan Cameron Signed-off-by: Dmitry Torokhov --- drivers/input/touchscreen/ads7846.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index c24946f51256..ab51a8dbdb5a 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -281,17 +281,25 @@ struct ser_req { u8 command; u8 ref_off; u16 scratch; - __be16 sample; struct spi_message msg; struct spi_transfer xfer[6]; + /* + * DMA (thus cache coherency maintenance) requires the + * transfer buffers to live in their own cache lines. + */ + __be16 sample ____cacheline_aligned; }; struct ads7845_ser_req { u8 command[3]; u8 pwrdown[3]; - u8 sample[3]; struct spi_message msg; struct spi_transfer xfer[2]; + /* + * DMA (thus cache coherency maintenance) requires the + * transfer buffers to live in their own cache lines. + */ + u8 sample[3] ____cacheline_aligned; }; static int ads7846_read12_ser(struct device *dev, unsigned command) -- 2.34.1