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Subject: Re: [PATCH] mmc: disable card sleep via device-tree
To: Lukasz Majewski <lukma@denx.de>,
        Stanislav Meduna <stanislav.meduna@nxtcontrol.com>
References: <20180422213126.32756-1-lukma@denx.de>
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        Chanho Min <chanho.min@lge.com>, <devicetree@vger.kernel.org>,
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From: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Message-ID: <f4b6291f-2756-38ff-31e0-0ba290f64e48@mentor.com>
Date: Mon, 23 Apr 2018 09:04:09 +0300
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Hi Lukasz,

On 04/23/2018 12:31 AM, Lukasz Majewski wrote:
> From: Stanislav Meduna <stanislav.meduna@nxtcontrol.com>
> 
> On a TQMa53 module the mmc_sleep leaves the eMMC card in a state
> that the imx53 rom boot code is unable to probe, resulting in
> reboot hanging. Add a device tree property to disable sleeping
> on suspend.
> 
> For TQMa53 modules the exact commit to cause hang after reboot
> (v3.10 -> v3.11):
> commit 486fdbbc1483 ("mmc: core: Add shutdown callback for (e)MMC bus_ops")
> 
> [The exact discussion can be found here:
> https://patchwork.kernel.org/patch/8881401/
> "i.MX53 restart via watchdog does not work"
> 
> Signed-off-by: Stanislav Meduna <stanislav.meduna@nxtcontrol.com>
> Signed-off-by: Lukasz Majewski <lukma@denx.de>
> ---
>  Documentation/devicetree/bindings/mmc/mmc-card.txt | 4 ++++
>  drivers/mmc/core/mmc.c                             | 7 +++++--
>  include/linux/mmc/card.h                           | 2 +-
>  3 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/mmc-card.txt b/Documentation/devicetree/bindings/mmc/mmc-card.txt
> index 8d2d71758907..c3ee151edd7c 100644
> --- a/Documentation/devicetree/bindings/mmc/mmc-card.txt
> +++ b/Documentation/devicetree/bindings/mmc/mmc-card.txt
> @@ -12,6 +12,9 @@ Required properties:
>  Optional properties:
>  -broken-hpi : Use this to indicate that the mmc-card has a broken hpi
>                implementation, and that hpi should not be used
> +-no-sleep-on-suspend : Do not put the card to sleep when suspending.
> +              There are boards with bootloaders that are unable
> +              to probe such card when rebooting.

I would recommend to examine an option to reuse the existing host
controller property 'keep-power-in-suspend', note that a particular
host controller driver may ignore it.

In general the problem sounds like a PCB hardware bug, and if it is
eMMC card specific, please provide more information about that eMMC
rather than about the host.

--
With best wishes,
Vladimir