linux-kernel - Re: [PATCH] mmc: dw_mmc: avoid long timeout if register invalid

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Message-ID: <cfe4476922584dff91bf0fdbec0c0843@hyperstone.com>
Date:   Wed, 29 Sep 2021 06:53:56 +0000
From:   Christian Löhle <CLoehle@...erstone.com>
To:     Jaehoon Chung <jh80.chung@...sung.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>
CC:     "marten.lindahl@...s.com" <marten.lindahl@...s.com>,
        "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>
Subject: Re: [PATCH] mmc: dw_mmc: avoid long timeout if register invalid

Hey,
so more generally the timeout here can be 41954 up to 167783 ms.
Is 42s too low to view it as invalid here?
Would you prefer the patch exluding the specific timeout values instead of anything above
41954?

Regards,
Christian




From: Jaehoon Chung <jh80.chung@...sung.com>
Sent: Friday, September 24, 2021 11:49 AM
To: Christian Löhle; linux-kernel@...r.kernel.org; linux-mmc@...r.kernel.org
Cc: marten.lindahl@...s.com; ulf.hansson@...aro.org
Subject: Re: [PATCH] mmc: dw_mmc: avoid long timeout if register invalid
    
Hi,

On 9/17/21 4:50 PM, Christian Löhle wrote:
> 
> Set the limit to 1s if the register is at reset value.
> 
> Signed-off-by: Christian Loehle <cloehle@...erstone.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;
> +

If dtrt_ms is 167sec, it means that bus_hz should be 0 or 1.
What value is your host->bus_hz?

Best Regards,
Jaehoon Chung

>        spin_lock_irqsave(&host->irq_lock, irqflags);
>        if (!test_bit(EVENT_DATA_COMPLETE, &host->pending_events))
>                mod_timer(&host->dto_timer,
> 

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