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Groups > linux.kernel > #1714080

[RFC PATCH v4 5/6] i2c: rcar: skip DMA if buffer is not safe

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This HW is prone to races, so it needs to setup new messages in irq
context. That means we can't alloc bounce buffers if a message buffer is
not DMA safe. So, in that case, simply fall back to PIO.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 drivers/i2c/busses/i2c-rcar.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 93c1a54981df08..5654a7142bffec 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -359,7 +359,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
 	int len;
 
 	/* Do not use DMA if it's not available or for messages < 8 bytes */
-	if (IS_ERR(chan) || msg->len < 8)
+	if (IS_ERR(chan) || msg->len < 8 || !(msg->flags & I2C_M_DMA_SAFE))
 		return;
 
 	if (read) {
-- 
2.11.0

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[RFC PATCH v4 0/6] i2c: document DMA handling and add helpers for it Wolfram Sang <wsa+renesas@sang-engineering.com> - 2017-08-17 16:20 +0200
  [RFC PATCH v4 4/6] i2c: sh_mobile: use helper to decide if DMA is useful Wolfram Sang <wsa+renesas@sang-engineering.com> - 2017-08-17 16:20 +0200
  [RFC PATCH v4 1/6] i2c: add a message flag for DMA safe buffers Wolfram Sang <wsa+renesas@sang-engineering.com> - 2017-08-17 16:20 +0200
  [RFC PATCH v4 5/6] i2c: rcar: skip DMA if buffer is not safe Wolfram Sang <wsa+renesas@sang-engineering.com> - 2017-08-17 16:20 +0200
  Re: [RFC PATCH v4 0/6] i2c: document DMA handling and add helpers  for it Jonathan Cameron <jic23@jic23.retrosnub.co.uk> - 2017-08-20 12:20 +0200

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