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Date:   Fri, 17 Sep 2021 15:41:23 +0200
From:   Jesper Nilsson <jesper.nilsson@axis.com>
To:     Christian =?iso-8859-1?Q?L=F6hle?= <CLoehle@hyperstone.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
        "marten.lindahl@axis.com" <marten.lindahl@axis.com>,
        "jh80.chung@samsung.com" <jh80.chung@samsung.com>,
        "ulf.hansson@linaro.org" <ulf.hansson@linaro.org>
Subject: Re: [PATCH] mmc: dw_mmc: avoid long timeout if register invalid
Message-ID: <20210917134123.GL12780@axis.com>
References: <bf19053cf6f547bcbb364975cda84c30@hyperstone.com>
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On Fri, Sep 17, 2021 at 07:50:44AM +0000, Christian L?hle wrote:
> Set the limit to 1s if the register is at reset value.

One second could be to short, we have seen some cards take up
to 10s on write operations. Although that was quite a few years ago.

TMOUT is only used for reads if I understand correctly,
so it should be ok anyways.

/Jesper

> Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
> ---
>  drivers/mmc/host/dw_mmc.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 6578cc64ae9e..cd9a6e0a7449 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1983,6 +1983,14 @@ static void dw_mci_set_drto(struct dw_mci *host)
>  	/* add a bit spare time */
>  	drto_ms += 10;
>  
> +	/*
> +	 * If TMOUT register still holds the reset value the above calculation
> +	 * would yield a timeout of over 167 seconds, limit it to 1000ms.
> +	 * Normal reads/writes should not take anywhere close to 120s.
> +	 */
> +	if (drto_ms > 120000)
> +		drto_ms = 1000;
> +
>  	spin_lock_irqsave(&host->irq_lock, irqflags);
>  	if (!test_bit(EVENT_DATA_COMPLETE, &host->pending_events))
>  		mod_timer(&host->dto_timer,
> -- 
> 2.32.0
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/^JN - Jesper Nilsson
-- 
               Jesper Nilsson -- jesper.nilsson@axis.com