linux-kernel - Re: [PATCH v2] mmc: meson: Fix usage of meson_mmc_post

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Message-ID: <CAPDyKFq797hihSwtX00V6tW2c035FLPnWonbBGcuh4L-zWqHTw@mail.gmail.com>
Date:   Mon, 28 Feb 2022 18:05:35 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Kevin Hilman <khilman@...libre.com>,
        Rong Chen <rong.chen@...ogic.com>
Cc:     Neil Armstrong <narmstrong@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        1131046452@...com, linux-mmc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        45581586@...com, Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: [PATCH v2] mmc: meson: Fix usage of meson_mmc_post_req()

+ Hainer

On Wed, 16 Feb 2022 at 13:42, Rong Chen <rong.chen@...ogic.com> wrote:
>
> Currently meson_mmc_post_req() is called in meson_mmc_request() right
> after meson_mmc_start_cmd(). This could lead to DMA unmapping before the request
> is actually finished.
>
> To fix, don't call meson_mmc_post_req() until meson_mmc_request_done().
>
> Signed-off-by: Rong Chen <rong.chen@...ogic.com>

We should probably add a fixes tag to this, right?
Fixes: 79ed05e329c3 ("mmc: meson-gx: add support for descriptor chain mode")

Moreover, you want this tagged for stable kernels too, right?

I have applied it for fixes and added the above tags, please tell if
you want me to change it.

Kind regards
Uffe


> ---
>  drivers/mmc/host/meson-gx-mmc.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 8f36536cb1b6..58ab9d90bc8b 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -173,6 +173,8 @@ struct meson_host {
>         int irq;
>
>         bool vqmmc_enabled;
> +       bool needs_pre_post_req;
> +
>  };
>
>  #define CMD_CFG_LENGTH_MASK GENMASK(8, 0)
> @@ -663,6 +665,8 @@ static void meson_mmc_request_done(struct mmc_host *mmc,
>         struct meson_host *host = mmc_priv(mmc);
>
>         host->cmd = NULL;
> +       if (host->needs_pre_post_req)
> +               meson_mmc_post_req(mmc, mrq, 0);
>         mmc_request_done(host->mmc, mrq);
>  }
>
> @@ -880,7 +884,7 @@ static int meson_mmc_validate_dram_access(struct mmc_host *mmc, struct mmc_data
>  static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
>  {
>         struct meson_host *host = mmc_priv(mmc);
> -       bool needs_pre_post_req = mrq->data &&
> +       host->needs_pre_post_req = mrq->data &&
>                         !(mrq->data->host_cookie & SD_EMMC_PRE_REQ_DONE);
>
>         /*
> @@ -896,22 +900,19 @@ static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
>                 }
>         }
>
> -       if (needs_pre_post_req) {
> +       if (host->needs_pre_post_req) {
>                 meson_mmc_get_transfer_mode(mmc, mrq);
>                 if (!meson_mmc_desc_chain_mode(mrq->data))
> -                       needs_pre_post_req = false;
> +                       host->needs_pre_post_req = false;
>         }
>
> -       if (needs_pre_post_req)
> +       if (host->needs_pre_post_req)
>                 meson_mmc_pre_req(mmc, mrq);
>
>         /* Stop execution */
>         writel(0, host->regs + SD_EMMC_START);
>
>         meson_mmc_start_cmd(mmc, mrq->sbc ?: mrq->cmd);
> -
> -       if (needs_pre_post_req)
> -               meson_mmc_post_req(mmc, mrq, 0);
>  }
>
>  static void meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)
> --
> 2.25.1
>