From ed5a81046bf7a1b665eb5bf178c4139503f4637e Mon Sep 17 00:00:00 2001
From: Wolfram Sang <wsa+renesas@sang-engineering.com>
Date: Tue, 5 Mar 2019 18:54:32 +0100
Subject: [PATCH] i2c: rcar: sanity check for minimal DMA length
Use a macro for the hardcoded value and apply a build check. If it is
not met, the driver logic will not work anymore.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
---
drivers/i2c/busses/i2c-rcar.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index a7578f6da97966..57083e91f2cfd1 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -85,6 +85,7 @@
/* ICFBSCR */
#define TCYC17 0x0f /* 17*Tcyc delay 1st bit between SDA and SCL */
+#define RCAR_MIN_DMA_LEN 8
#define RCAR_BUS_PHASE_START (MDBS | MIE | ESG)
#define RCAR_BUS_PHASE_DATA (MDBS | MIE)
@@ -412,8 +413,8 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
int len;
/* Do various checks to see if DMA is feasible at all */
- if (IS_ERR(chan) || msg->len < 8 || !(msg->flags & I2C_M_DMA_SAFE) ||
- (read && priv->flags & ID_P_NO_RXDMA))
+ if (IS_ERR(chan) || msg->len < RCAR_MIN_DMA_LEN ||
+ !(msg->flags & I2C_M_DMA_SAFE) || (read && priv->flags & ID_P_NO_RXDMA))
return;
if (read) {
@@ -921,6 +922,9 @@ static int rcar_i2c_probe(struct platform_device *pdev)
struct i2c_timings i2c_t;
int irq, ret;
+ /* Otherwise logic will break because some bytes must always use PIO */
+ BUILD_BUG_ON_MSG(RCAR_MIN_DMA_LEN < 3, "Invalid min DMA length");
+
priv = devm_kzalloc(dev, sizeof(struct rcar_i2c_priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
--
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