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Diffstat (limited to 'drivers/i2c/busses/i2c-rcar.c')
-rw-r--r--drivers/i2c/busses/i2c-rcar.c30
1 files changed, 16 insertions, 14 deletions
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index a7578f6da979..d39a4606f72d 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)
@@ -398,7 +399,7 @@ static void rcar_i2c_dma_callback(void *data)
rcar_i2c_dma_unmap(priv);
}
-static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
+static bool rcar_i2c_dma(struct rcar_i2c_priv *priv)
{
struct device *dev = rcar_i2c_priv_to_dev(priv);
struct i2c_msg *msg = priv->msg;
@@ -412,9 +413,9 @@ 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))
- return;
+ if (IS_ERR(chan) || msg->len < RCAR_MIN_DMA_LEN ||
+ !(msg->flags & I2C_M_DMA_SAFE) || (read && priv->flags & ID_P_NO_RXDMA))
+ return false;
if (read) {
/*
@@ -434,7 +435,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
dma_addr = dma_map_single(chan->device->dev, buf, len, dir);
if (dma_mapping_error(chan->device->dev, dma_addr)) {
dev_dbg(dev, "dma map failed, using PIO\n");
- return;
+ return false;
}
sg_dma_len(&priv->sg) = len;
@@ -448,7 +449,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
if (!txdesc) {
dev_dbg(dev, "dma prep slave sg failed, using PIO\n");
rcar_i2c_cleanup_dma(priv);
- return;
+ return false;
}
txdesc->callback = rcar_i2c_dma_callback;
@@ -458,7 +459,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
if (dma_submit_error(cookie)) {
dev_dbg(dev, "submitting dma failed, using PIO\n");
rcar_i2c_cleanup_dma(priv);
- return;
+ return false;
}
/* Enable DMA Master Received/Transmitted */
@@ -468,6 +469,7 @@ static void rcar_i2c_dma(struct rcar_i2c_priv *priv)
rcar_i2c_write(priv, ICDMAER, TMDMAE);
dma_async_issue_pending(chan);
+ return true;
}
static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
@@ -478,6 +480,10 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
if (!(msr & MDE))
return;
+ /* Check if DMA can be enabled and take over */
+ if (priv->pos == 1 && rcar_i2c_dma(priv))
+ return;
+
if (priv->pos < msg->len) {
/*
* Prepare next data to ICRXTX register.
@@ -488,13 +494,6 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
*/
rcar_i2c_write(priv, ICRXTX, msg->buf[priv->pos]);
priv->pos++;
-
- /*
- * Try to use DMA to transmit the rest of the data if
- * address transfer phase just finished.
- */
- if (msr & MAT)
- rcar_i2c_dma(priv);
} else {
/*
* The last data was pushed to ICRXTX on _PREV_ empty irq.
@@ -921,6 +920,9 @@ 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;