Re: [PATCH V4 03/15] mmc: core: Add support for re-tuning before each request

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

On 01/04/15 13:13, Ulf Hansson wrote:
> On 27 March 2015 at 21:57, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> At the start of each request, re-tune if needed and
>> then hold off re-tuning again until the request is done.
>>
>> Note that though there is one function that starts
>> requests (mmc_start_request) there are two that wait for
>> the request to be done (mmc_wait_for_req_done and
>> mmc_wait_for_data_req_done).  Also note that
>> mmc_wait_for_data_req_done can return even when the
>> request is not done (which allows the block driver
>> to prepare a newly arrived request while still
>> waiting for the previous request).
>>
>> This patch ensures re-tuning is held for the duration
>> of a request.  Subsequent patches will also hold
>> re-tuning at other times when it might cause a
>> conflict.
> 
> How about holding of re-tune from __mmc_claim_host() (after
> pm_runtime_get_sync() ) -> mmc_release_host(). Would that work? If so,
> that would simplify a lot around this.

I don't think it would work. The host is claimed both when we want to do
re-tuning (timer, CRC error, or host requests it) and when we want to
prevent it (in between dependent commands like erase, polling when card is
busy, SDIO card custom wake-up command).