linux-kernel - Re: [PATCH] mmc: mediatek: fix request blocked by cancel_delayed

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Message-ID: <CAPDyKFrXVaq85sSQ+ib-U=rgdxB_k2tif0aHQi_0d8kZ2FZDcA@mail.gmail.com>
Date:	Fri, 22 Apr 2016 14:24:44 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Chaotian Jing <chaotian.jing@...iatek.com>
Cc:	Matthias Brugger <matthias.bgg@...il.com>,
	Nicolas Boichat <drinkcat@...omium.org>,
	Douglas Anderson <dianders@...omium.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-mediatek@...ts.infradead.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	srv_heupstream <srv_heupstream@...iatek.com>,
	Sascha Hauer <kernel@...gutronix.de>
Subject: Re: [PATCH] mmc: mediatek: fix request blocked by cancel_delayed_work

On 18 April 2016 at 09:13, Chaotian Jing <chaotian.jing@...iatek.com> wrote:
> there are 2 points will cause could not call mmc_request_done()
> and eventually cause the caller thread blocked.
>
> A. if card was busy, cancel_delayed_work() will return false because
> the delay work has not been scheduled, in this case, need put
> mod_delayed_work() in front of msdc_cmd_is_ready()
>
> B. if a request really need more than 5s(Some Sandisk TF card), it will
> use cancel_delayed_work() to cancel itself, and also return false, so use
> in_interrupt() to avoid this case
>
> Signed-off-by: Chaotian Jing <chaotian.jing@...iatek.com>
> ---
>  drivers/mmc/host/mtk-sd.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index b17f30d..1511b1b 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -724,7 +724,7 @@ static void msdc_request_done(struct msdc_host *host, struct mmc_request *mrq)
>         bool ret;
>
>         ret = cancel_delayed_work(&host->req_timeout);
> -       if (!ret) {
> +       if (!ret && in_interrupt()) {
>                 /* delay work already running */
>                 return;
>         }
> @@ -824,7 +824,12 @@ static inline bool msdc_cmd_is_ready(struct msdc_host *host,
>         }
>
>         if (mmc_resp_type(cmd) == MMC_RSP_R1B || cmd->data) {
> -               tmo = jiffies + msecs_to_jiffies(20);
> +               /*
> +                * 2550ms is from EXT_CSD[248], after switch to hs200,
> +                * using CMD13 to polling card status, it will get response
> +                * of 0x800, but EMMC still pull-low DAT0.
> +                */

Seems like you are solving a eMMC specific issue on your driver?

Perhaps we should try to use a card quirk instead?


> +               tmo = jiffies + msecs_to_jiffies(2550);
>                 /* R1B or with data, should check SDCBUSY */
>                 while ((readl(host->base + SDC_STS) & SDC_STS_SDCBUSY) &&
>                                 time_before(jiffies, tmo))
> @@ -847,6 +852,7 @@ static void msdc_start_command(struct msdc_host *host,
>         WARN_ON(host->cmd);
>         host->cmd = cmd;
>
> +       mod_delayed_work(system_wq, &host->req_timeout, DAT_TIMEOUT);
>         if (!msdc_cmd_is_ready(host, mrq, cmd))
>                 return;
>
> @@ -858,7 +864,6 @@ static void msdc_start_command(struct msdc_host *host,
>
>         cmd->error = 0;
>         rawcmd = msdc_cmd_prepare_raw_cmd(host, mrq, cmd);
> -       mod_delayed_work(system_wq, &host->req_timeout, DAT_TIMEOUT);
>
>         sdr_set_bits(host->base + MSDC_INTEN, cmd_ints_mask);
>         writel(cmd->arg, host->base + SDC_ARG);
> --
> 1.8.1.1.dirty
>

Kind regards
Uffe