linux-kernel - Re: [PATCH] mmc: sdio: Fix sdio wait busy implement limitation

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Message-ID: <CAPDyKFrDNBFV=1PtiopXoc+Zd7Tc-MZnR5k4za4Grbbs1aCP4Q@mail.gmail.com>
Date:   Thu, 20 Apr 2017 15:27:16 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     jiajie.hao@...iatek.com
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Chaotian Jing <chaotian.jing@...iatek.com>,
        Yong Mao <yong.mao@...iatek.com>,
        Eddie Huang <eddie.huang@...iatek.com>,
        srv_heupstream <srv_heupstream@...iatek.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-mediatek@...ts.infradead.org, linux-arm-kernel@...iatek.com
Subject: Re: [PATCH] mmc: sdio: Fix sdio wait busy implement limitation

On 17 April 2017 at 10:09,  <jiajie.hao@...iatek.com> wrote:
> From: Jiajie Hao <jiajie.hao@...iatek.com>
>
> The host may issue an I/O abort by writing to the CCCR at any time
> during I/O read operation via CMD52. And host may need suspend
> transcation during write busy stage in SDIO suspend/resume scenario.
> From other side, a card may accept CMD52 during data transfer phase.
>
> Previous implement would block issuing above command in busy stage.
> It cause function driver can't implement as proper way and has no
> opportunity to do some coverage in error case via I/O abort etc.
>
> We need bypass some necessary operation during busy check stage.
>
> Change-Id: Ib5a4599a2a98cbcf441b564f5f6fbb10c8a59e1b

Please remove this.

> Signed-off-by: Jiajie Hao <jiajie.hao@...iatek.com>
> ---
>  drivers/mmc/core/core.c     |    4 +++-
>  drivers/mmc/core/sdio_ops.h |   10 ++++++++++
>  2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 926e0fd..9c9a4bc 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -234,8 +234,10 @@ static void __mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>         /*
>          * For sdio rw commands we must wait for card busy otherwise some
>          * sdio devices won't work properly.
> +        * And bypass I/O abort, reset and bus suspend operations.
>          */
> -       if (mmc_is_io_op(mrq->cmd->opcode) && host->ops->card_busy) {
> +       if (mmc_is_io_op(mrq->cmd->opcode) && host->ops->card_busy &&
> +           !mmc_is_io_bypass(mrq->cmd->opcode, mrq->cmd->arg)) {

Instead of adding yet another function, let's extend the existing
mmc_is_io_op() to cover this new cases as well.

Moreover, to be reflect the purpose of the function, I suggest we
rename it from mmc_is_io_op() to sdio_is_op_busy().

>                 int tries = 500; /* Wait aprox 500ms at maximum */
>
>                 while (host->ops->card_busy(host) && --tries)
> diff --git a/drivers/mmc/core/sdio_ops.h b/drivers/mmc/core/sdio_ops.h
> index bed8a83..9896696 100644
> --- a/drivers/mmc/core/sdio_ops.h
> +++ b/drivers/mmc/core/sdio_ops.h
> @@ -31,5 +31,15 @@ static inline bool mmc_is_io_op(u32 opcode)
>         return opcode == SD_IO_RW_DIRECT || opcode == SD_IO_RW_EXTENDED;
>  }
>
> +static inline bool mmc_is_io_bypass(u32 opcode, u32 arg)
> +{
> +       u32 addr;
> +
> +       addr = (arg >> 9) & 0x1FFFF;
> +
> +       return ((opcode == SD_IO_RW_DIRECT) &&
> +               (addr == SDIO_CCCR_ABORT || addr == SDIO_CCCR_SUSPEND));
> +}
> +
>  #endif
>
> --
> 1.7.9.5
>

Kind regards
Uffe