diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-rcar.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-rcar.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index dd52a068b140..a7578f6da979 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -363,9 +363,6 @@ static void rcar_i2c_dma_unmap(struct rcar_i2c_priv *priv) struct dma_chan *chan = priv->dma_direction == DMA_FROM_DEVICE ? priv->dma_rx : priv->dma_tx; - /* Disable DMA Master Received/Transmitted */ - rcar_i2c_write(priv, ICDMAER, 0); - dma_unmap_single(chan->device->dev, sg_dma_address(&priv->sg), sg_dma_len(&priv->sg), priv->dma_direction); @@ -375,6 +372,9 @@ static void rcar_i2c_dma_unmap(struct rcar_i2c_priv *priv) priv->flags |= ID_P_NO_RXDMA; priv->dma_direction = DMA_NONE; + + /* Disable DMA Master Received/Transmitted, must be last! */ + rcar_i2c_write(priv, ICDMAER, 0); } static void rcar_i2c_cleanup_dma(struct rcar_i2c_priv *priv) @@ -611,6 +611,15 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv) return true; } +/* + * This driver has a lock-free design because there are IP cores (at least + * R-Car Gen2) which have an inherent race condition in their hardware design. + * There, we need to clear RCAR_BUS_MASK_DATA bits as soon as possible after + * the interrupt was generated, otherwise an unwanted repeated message gets + * generated. It turned out that taking a spinlock at the beginning of the ISR + * was already causing repeated messages. Thus, this driver was converted to + * the now lockless behaviour. Please keep this in mind when hacking the driver. + */ static irqreturn_t rcar_i2c_irq(int irq, void *ptr) { struct rcar_i2c_priv *priv = ptr; |