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

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On 27 March 2015 at 21:57, Adrian Hunter <adrian.hunter@xxxxxxxxx> 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.

Kind regards
Uffe

>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
>  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 2679264..bb50d82 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
>
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