linux-kernel - Re: [PATCH v1 2/2] mmc: core: No need to calculate the timeout value for CQE data transmission

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Message-ID: <CAPDyKFpC6iei96n-UcRTNrxTaHeejzfQX+rka7GSwSZjXN7-4g@mail.gmail.com>
Date:   Tue, 14 Sep 2021 10:13:48 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Bean Huo <huobean@...il.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Avri Altman <avri.altman@....com>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Bean Huo (beanhuo)" <beanhuo@...ron.com>
Subject: Re: [PATCH v1 2/2] mmc: core: No need to calculate the timeout value
 for CQE data transmission

On Tue, 7 Sept 2021 at 17:12, Bean Huo <huobean@...il.com> wrote:
>
> From: Bean Huo <beanhuo@...ron.com>
>
> In case CQE is enabled, the timeout value of data transmission is always
> set to be maximum in sdhci_cqe_enable(), so, calculating its timeout value
> is obviously superfluous. Change to return directly, which can save some CPU
> cycle time.
>
> Signed-off-by: Bean Huo <beanhuo@...ron.com>
> ---
>  drivers/mmc/core/core.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 240c5af793dc..0b571a3bc988 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -649,6 +649,7 @@ EXPORT_SYMBOL(mmc_wait_for_cmd);
>  void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
>  {
>         unsigned int mult;
> +       struct mmc_host *host = card->host;
>
>         /*
>          * SDIO cards only define an upper 1 s limit on access.
> @@ -659,6 +660,13 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
>                 return;
>         }
>
> +       /*
> +        * In case CQE is enabled, the timeout will be set a maximum timeout in
> +        * sdhci_cqe_enable(), so, no need to go through the below algorithm.
> +        */
> +       if (host->cqe_enabled)

 I don't think this is a good idea. For example, host->cqe_enabled is
set for the hsq case well.

> +               return;
> +
>         /*
>          * SD cards use a 100 multiplier rather than 10
>          */

Kind regards
Uffe