Re: [patch] split MMC_CAP_4_BIT_DATA

[Pierre Ossman]

On Thu, 10 Jan 2008 17:22:55 +0800
"Bryan Wu" <cooloney.lkml@xxxxxxxxx> wrote:

> 
> At page 4-3 of  ADSP-BF54x Blackfin(R) Processor Peripheral Hardware
> Reference, there is a table which guide us the SDH controller does not
> support 4-bit mode MMC card. Please found the table picture in the
> attachment or get the document at:
> http://www.analog.com/UploadedFiles/Associated_Docs/61460151169789ADSP_BF54x_Blackfin_Processor_Peripheral_Hardware_Reference.pdf
> 

Ok, but this just means the controller wasn't designed with 4-bit MMC in mind. As several other "SD-only" controller have been tested with modern MMC cards without a problem, this is not sufficient to explain any problem.

> 
> Thanks, actually we are not yet convinced  by our hardware designer
> why BF54x SDH does not support 4-bit MMC.
> 

Please keep me informed on how it progresses. I'd like an at least plausible explanation, preferably also some empirical data, before I'm ready to accept Mike's patch.

Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org
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