Re: [PATCH V6 03/15] mmc: core: Add support for re-tuning before each request

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

On 04/05/15 16:28, Ulf Hansson wrote:
> On 20 April 2015 at 14:09, 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.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> 
> Patch2 is calling mmc_retune_needed() and thus actually triggers a
> re-tune to potentially happen.

That won't happen because host->retune_period is not set, so
mmc_retune_needed() won't be called.

> 
> To avoid bisectability issues about not holding re-tune when needed, I
> suggest we move $subject patch to after patch8.
> 
> Kind regards
> Uffe
> 
>> ---
>>  drivers/mmc/core/core.c | 32 +++++++++++++++++++++++++-------
>>  1 file changed, 25 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index dd43f9b..a9936cb 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -186,12 +186,29 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
>>
>>  EXPORT_SYMBOL(mmc_request_done);
>>
>> +static void __mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>> +{
>> +       int err;
>> +
>> +       /* Assumes host controller has been runtime resumed by mmc_claim_host */
>> +       err = mmc_retune(host);
>> +       if (err) {
>> +               mrq->cmd->error = err;
>> +               mmc_request_done(host, mrq);
>> +               return;
>> +       }
>> +
>> +       host->ops->request(host, mrq);
>> +}
>> +
>>  static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>>  {
>>  #ifdef CONFIG_MMC_DEBUG
>>         unsigned int i, sz;
>>         struct scatterlist *sg;
>>  #endif
>> +       mmc_retune_hold(host);
>> +
>>         if (mmc_card_removed(host->card))
>>                 return -ENOMEDIUM;
>>
>> @@ -252,7 +269,7 @@ static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>>         }
>>         mmc_host_clk_hold(host);
>>         led_trigger_event(host->led, LED_FULL);
>> -       host->ops->request(host, mrq);
>> +       __mmc_start_request(host, mrq);
>>
>>         return 0;
>>  }
>> @@ -422,17 +439,16 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host,
>>                                         cmd->opcode, cmd->error);
>>                                 cmd->retries--;
>>                                 cmd->error = 0;
>> -                               host->ops->request(host, mrq);
>> +                               __mmc_start_request(host, mrq);
>>                                 continue; /* wait for done/new event again */
>>                         }
>>                 } else if (context_info->is_new_req) {
>>                         context_info->is_new_req = false;
>> -                       if (!next_req) {
>> -                               err = MMC_BLK_NEW_REQUEST;
>> -                               break; /* return err */
>> -                       }
>> +                       if (!next_req)
>> +                               return MMC_BLK_NEW_REQUEST;
>>                 }
>>         }
>> +       mmc_retune_release(host);
>>         return err;
>>  }
>>
>> @@ -471,8 +487,10 @@ static void mmc_wait_for_req_done(struct mmc_host *host,
>>                          mmc_hostname(host), cmd->opcode, cmd->error);
>>                 cmd->retries--;
>>                 cmd->error = 0;
>> -               host->ops->request(host, mrq);
>> +               __mmc_start_request(host, mrq);
>>         }
>> +
>> +       mmc_retune_release(host);
>>  }
>>
>>  /**
>> --
>> 1.9.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
>