linux-kernel - [PATCH v6 9/9] i2c: rcar: skip DMA if buffer is not safe

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Message-Id: <20171104202009.3818-10-wsa+renesas@sang-engineering.com>
Date:   Sat,  4 Nov 2017 21:20:09 +0100
From:   Wolfram Sang <wsa+renesas@...g-engineering.com>
To:     linux-i2c@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-input@...r.kernel.org,
        linux-media@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: [PATCH v6 9/9] i2c: rcar: skip DMA if buffer is not safe

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.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Wolfram Sang <wsa+renesas@...g-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 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