Re: relation between mmc_request, mmc_data and mmc_command

Re: relation between mmc_request, mmc_data and mmc_command

[Pierre Ossman]

[-- Attachment #1: Type: text/plain, Size: 922 bytes --]

On Sun, 23 Dec 2007 23:25:26 -0800
"raki john" <raki4652@gmail.com> wrote:

> 
> Does  mmc_requeest->stop is equal  to mmc_request->data->stop ?
> 
> Does  mmc_request   is equal  to mmc_request->data->mrq ?
> 
> Does mmc_request->data   is equal  to   mmc_request->cmd->data ?
> 
> Does mmc_request   is equal  to mmc_request->cmd->mrq  ?
> 

Yes on all accounts. I don't know the reason for this extreme redundancy. It was there long before I got involved.

> 
> I think Stop command which is part of mmc_request is used for sending stop
> command after Multi Block write. is this correct. If stop command fails(CRC
> fail, timeout), does this mean card  write failed.
> 

It is correct that it is used for multi block writes. But also other open ended transfers.

If the stop command fails, then the card will be in an unknown state. The write should have been completed though.

Rgds
Pierre

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 197 bytes --]

relation between mmc_request, mmc_data and mmc_command

[raki john]

Hi All,
what is the relation between mmc_request ,  mmc_data and mmc_command .
(I am new SD driver development, and I  am working on 2.6.22.1)
when mmc core layer calls  Host controllers request function (member
of  struct  mmc_host_ops), it passes mmc_request structure   to
driver's request function.

1)mmc_request has three members
    mmc_command * cmd
    mmc_data *  data
    mmc_command * stop

2) mmc_data has
mmc_command * stop
 mmc_request *  mrq


3) mmc_command has
   mmc_data *data
  mmc_request *mrq


Does  mmc_requeest->stop is equal  to mmc_request->data->stop ?

Does  mmc_request   is equal  to mmc_request->data->mrq ?

Does mmc_request->data   is equal  to   mmc_request->cmd->data ?

Does mmc_request   is equal  to mmc_request->cmd->mrq  ?


I think Stop command which is part of mmc_request is used for sending
stop command after Multi Block write. is this correct. If stop command
fails(CRC fail, timeout), does this mean card  write failed.



 Thanks In Advance  for your help

--
Thanks
raki