linux-kernel - Re: [PATCH v2 2/2] mmc: core: adjust polling interval for CMD1

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Message-ID: <CAMy0x0mUO3Sv-87MTvkn+hpYtKeWW7bEWSrjMopqupFytpOCpQ@mail.gmail.com>
Date:   Mon, 8 Nov 2021 23:29:07 +0900
From:   Huijin Park <bbanghj.park@...il.com>
To:     Avri Altman <Avri.Altman@....com>
Cc:     Huijin Park <huijin.park@...sung.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] mmc: core: adjust polling interval for CMD1

2021년 11월 4일 (목) 오후 4:27, Avri Altman <Avri.Altman@....com>님이 작성:
>
>
> > In mmc_send_op_cond(), loops are continuously performed at the same
> > interval of 10 ms.  However the behaviour is not good for some eMMC which
> > can be out from a busy state earlier than 10 ms if normal.
> >
> > Rather than fixing about the interval time in mmc_send_op_cond(), let's
> > instead convert into using the common __mmc_poll_for_busy().
> >
> > The reason for adjusting the interval time is that it is important to reduce the
> > eMMC initialization time, especially in devices that use eMMC as rootfs.
> That's an impressive improvement.
> Can you share some of the use-cases in which 10ms reduction in boot time is required?

It can be used as one of the improvements and tuning items that
can make rootfs preparation faster for cold booting.
(e.g. if it is delayed, it outputs "Waiting for root device.." log.)
Above all, I think it is not desirable to delay even though mmc
initialization is done.

Thanks,

>
> Thanks,
> Avri