[RFC PATCH v5 5/6] i2c: rcar: skip DMA if buffer is not safe

From: Wolfram Sang
Date: Wed Sep 20 2017 - 15:00:45 EST


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@xxxxxxxxxxxxxxxxxxxx>
---
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 15d764afec3b29..8a2ae3e6c561c4 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