Re: MMCv4 support (8-bit support missing)

[Pierre Ossman <drzeus@drzeus.cx>]

Madhusudhan c wrote:
> Hi Pierre/philip,
> 

Hi Madhusudhan,

Feel free to add me as cc in the future if you want me to notice your mail ;)

> This is regarding the MMCv4 support that came in as part of the MMC
> core of 2.6.20 linux kernel version.
> 
> The high speed MMC cards can support 4-bit/8-bit transfers. The 8-bit
> support seems to be missing from the MMCv4 support implemented by
> Philip Langdale .

As soon as hardware with specs is available we'll start hacking. :)

> To support 8-bit transfers the core needs to implement "bus testing
> procedure". This requires support for CMD19 and CMD14.
> 
> Why is the support for bus testing procedure msiing from the MMCv4 support?
> 

We haven't determined it as necessary, and as Philip commented, most (if not
all) controllers cannot properly support the test.

Rgds
Pierre

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