[PATCH v9 3/3] i2c: imx: add DMA support for freescale i2c driver

Wolfram Sang wsa at the-dreams.de
Sat Nov 8 09:35:13 PST 2014


mostly looking good...

> +#define IMX_I2C_DMA_THRESHOLD	16

Have you guessed or measured this value? A comment about this value
would be nice.

> +struct imx_i2c_dma {
> +	struct dma_chan		*chan_tx;
> +	struct dma_chan		*chan_rx;
> +	struct dma_chan		*chan_using;
> +	struct completion	cmd_complete;
> +	dma_addr_t		dma_buf;
> +	unsigned int		dma_len;
> +	unsigned int		dma_transfer_dir;
> +	unsigned int		dma_data_dir;

Please use proper types as there are things like 'enum
dma_data_direction' and the likes...

> +	dmaengine_submit(txdesc);

This can fail, too. Use dma_submit_error() to check.

> +	result = wait_for_completion_interruptible_timeout(
> +				&i2c_imx->dma->cmd_complete,
> +				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));

Have you tested signals extensively? I can't really recommend the
_intrruptible_ here. I don't see any cleaning up to get the bus to a
consistent state again. Most people drop the interruptible sooner or

> +	/* Init DMA config if support*/
> +	i2c_imx_dma_request(i2c_imx, phy_addr);

Make this function void? DMA is optional anyhow.



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