Re: [PATCH V2 00/15] mmc: host: Add facility to support re-tuning

[Adrian Hunter <adrian.hunter@intel.com>]

On 29/01/15 11:00, Adrian Hunter wrote:
> Hi
> 
> Here is V2 of some patches to move re-tuning support
> out of sdhci and into the core, and add support for HS400
> re-tuning.
> 
> Currently sdhci does re-tuning transparently by
> calling sdhci_execute_tuning() from its ->request()
> function.
> 
> The problem with HS400 re-tuning is that it must be
> done in HS200 mode. That means using switch commands
> and making ios changes. That means it potentially
> conflicts with other command sequences. The new
> re-tuning support accomodates that, however it is
> not strictly necessary because HS400 re-tuning
> should only be needed after runtime suspend when
> there would not be a conflict.
> 
> Nevertheless, this approach has more structure
> and potentially more flexibility.
> 
> Changes in V2:
> 
>     Added support to the block driver for re-tuning
>     and retrying after a CRC error. The host driver
>     is left to decide when an error indicates re-tuning
>     is needed. The block driver will retry a data request
>     once if re-tuning is flagged as needed.
> 
>     SDIO drivers need not be aware of re-tuning because
>     retrying will anyway cause re-tuning when re-tuning
>     is flagged as needed. Nevertheless SDIO drivers could
>     use the need_retune flag to instigate a retry when
>     otherwise they might not have.

Ulf, Arend, is this OK?