Re: [RFC PATCH v3 2/5] Documentation: synopsys-dw-mshc: add bindings for idmac and edmac

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

在 2015/8/6 10:20, Jaehoon Chung 写道:
> On 08/06/2015 11:16 AM, Doug Anderson wrote:
>> Shawn,
>>
>> On Wed, Aug 5, 2015 at 1:17 AM, Shawn Lin <shawn.lin@rock-chips.com> wrote:
>>> synopsys-dw-mshc supports three types of transfer mode. We add bindings
>>> and description for how to use them at runtime. Without idmac and edmac
>>> property, pio is the default transfer mode. Make sure that Idmac and emdac
>>> should not be used simultaneously.
>> Can't you just read the HCON register?
>>
>> [17:16]: DMA_INTERFACE
>>   00: none
>>   01: DW_DMA
>>   10: GENERIC_DMA
>>   11: NON-DW-DMA
> If read it and get the exactly information. I think we can use that information.

  It's helpful really, but the description is ambiguous. ：(
  So I make a big big mistake when I read it for the firest time .
  I was just wondering the "mismatch" value from HCON and my databook.

Here I get details from our ASIC team guy :

// Name:         DMA_INTERFACE
// Default:      None
// Values:       None (0), DW-DMA (1), Generic-DMA (2), NON-DW-DMA (3)
// Enabled:      INTERNAL_DMAC==0
//
// Configures the type for DMA interface. In addition to AMBA host 
interface,
//  the data FIFO can be accesses by the optional DMA interface. The DMA 
type
//  could be either DW-DMA, which provides hand shake signals to 
DW_ahb_dmac
//  controller, or a generic DMA interface which provides a simpler
//  request/acknowledgement protocol and dedicated DMA data-bus, or
//  no DMA interface.
`define DMA_INTERFACE 1

   if we use idmac, DMA_INTERFACE should be "0", and we get 2b'00 from 
HCON[17:16]
   if we use edmac, DMA_INTERFACE should be "1", "2" and we get 2b'01 ,2b'10
   from HCON[17:16] respectively .
   But if only support PIO mode,   DMA_INTERFACE should be "3", and we 
get 2b'11 from
   HCON[17:16].

   So, "none" means IDMAC, "DW_DMA"/"GENERIC_DMA" refer to two types of 
external dma and "NON-DW-DMA" means pio from databook . It's a little 
difficult to understand it.

  This makes my work easy!

  Thanks, Doug and Jeahoon.

> Best Regards,
> Jaehoon Chung
>
>
>
>


-- 
Shawn Lin