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

[Shawn Lin <shawn.lin@rock-chips.com>]

在 2015/8/5 16:49, Heiko Stübner 写道:
> 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].
    I  agree.  "trans_mode" is redundant here since it does the same 
work as "use_dma" to some degree.
    Thanks.
>
> Heiko
>
> [0] https://lkml.org/lkml/2015/8/3/407
>
>
>


-- 
Shawn Lin