Re: [RFC PATCH v3 1/5] mmc: dw_mmc: Add external dma interface support

["Heiko Stübner" <heiko@sntech.de>]

Am Mittwoch, 5. August 2015, 16:17:28 schrieb Shawn Lin:
> DesignWare MMC Controller can supports two types of DMA
> mode: external dma and internal dma. We get a RK312x platform
> integrated dw_mmc and ARM pl330 dma controller. This patch add
> edmac ops to support these platforms. I've tested it on RK312x
> platform with edmac mode and RK3288 platform with idmac mode.
> 
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> 
> ---

[...]

> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
> index 5be9767..6c1c7ea 100644
> --- a/include/linux/mmc/dw_mmc.h
> +++ b/include/linux/mmc/dw_mmc.h
> @@ -16,6 +16,7 @@
> 
>  #include <linux/scatterlist.h>
>  #include <linux/mmc/core.h>
> +#include <linux/dmaengine.h>
> 
>  #define MAX_MCI_SLOTS	2
> 
> @@ -40,6 +41,17 @@ enum {
> 
>  struct mmc_data;
> 
> +enum {
> +	TRANS_MODE_PIO = 0,
> +	TRANS_MODE_IDMAC,
> +	TRANS_MODE_EDMAC
> +};
> +
> +struct dw_mci_dma_slave {
> +	struct dma_chan *ch;
> +	enum dma_transfer_direction direction;
> +};
> +
>  /**
>   * struct dw_mci - MMC controller state shared between all slots
>   * @lock: Spinlock protecting the queue and associated data.
> @@ -147,17 +159,23 @@ struct dw_mci {
> 
>  	/* DMA interface members*/
>  	int			use_dma;
> +	int			trans_mode;

you're introducing this new trans_mode, but we have "use_dma" already.

So you could just define

enum {
	TRANS_DMA_PIO = 0,
	TRANS_DMA_IDMAC,
	TRANS_DMA_EDMAC
};

and fill use_dma appropriately. "0" is meaning PIO already, which I also did fix 
up some days ago in "[PATCH] mmc: dw_mmc: fix pio mode when internal dmac is 
enabled" [0].


Heiko

[0] https://lkml.org/lkml/2015/8/3/407