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From: =?utf-8?B?7J207Iq57Z2s?= <sh043.lee@samsung.com>
To: "'Ulf Hansson'" <ulf.hansson@linaro.org>
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Subject: RE: [PATCH] mmc: sd: Add a variable to check a faulty device
Date: Fri, 16 Feb 2024 10:14:15 +0900
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> -----Original Message-----
> > > On Tue, 13 Feb 2024 at 06:13, Seunghui Lee <sh043.lee=40samsung.com>
> wrote:
> > > >
> > > > In mobile devices, suspend/resume situations are frequent.
> > > > In the case of a defective SD card in which initialization fails,
> > > > unnecessary initialization time is consumed for each resume.
> > > > A field is needed to check that SD card initialization has failed
> > > > on the host. It could be used to remove unnecessary initialization.
> > >
> > > It's not clear to me, under what circumstance you want to optimize fo=
r.
> > >
> > > Is the SD card ever getting properly initialized during boot?
> > >
> > > Kind regards
> > > Uffe
> > >
> > We receive a lot of reports about SD card issues in the market.
> > There was no problem with the first time at the time of use, and there
> are many cases where people recognize that it is not recognized later on.
> In most cases, this is a problem with the SD card itself.
>=20
> Right. Thanks for clarifying.
>=20
> A follow up question from me is then, do you know more exactly *why* the
> SD cards encounter problems?
>=20
> In the past people have told me that powering on/off an SD card during
> system suspend/resume, too frequently, could damage the card. For non-
> removable cards, the card stays powered-off even after a system resume,
> but instead gets powered-on (and re-initialized) when there is a new
> request for it.
>=20
> In other words, if the problem is related to too frequent powering on/off
> the card, my advice would be to test with having the card set non-
> removable (the DT property for this is =22non-removable=22), to see if th=
at
> can help. If that solves the problem, we can work towards another common
> solution instead.
>=20

I understand your focus on finding the root cause of the problem.
However, unlike internal storage, there is a limit to analyzing cards that =
have problems in the market.
This is because there are many different SD card manufacturers and many man=
ufacturers leave it to OEMs.

For deferred resume, a responsiveness problem occurs on the user side on mo=
bile devices.
The response time of the initializing SD card initialization in the applica=
tion seems to be slow.
Currently, it seems to be a good structure for the first initialization at =
runtime resume.

Regarding non-removable,
We will test if we are given an opportunity to further analyze the cards oc=
curring in the market.
However, SD card detection is also used as a wakeup source and must be inse=
rted/removed so I'll consider it for testing purposes.

Thank you for the good suggestions though.

> >
> > SD card users cannot determine whether or not an SD card is a problem,
> so they should be guided in this regard.
> > It is necessary to distinguish whether the SD card is inserted but
> unrecognized or the SD card itself is not inserted, and if there is a
> field that can check for initialization failure, it will facilitate
> guidance, so we considered the patch.
> >
> > The variable's usage is expected to be used through the sysfs node in
> the vendor module.
>=20
> As Greg said, please provide the complete code.
>=20
> Although, I want to stress already at this point, I don't see a solution
> with sysfs being the correct thing to do here. The kernel should be able
> to manage this problem itself.
>=20
> =5B...=5D
>=20
> Kind regards
> Uffe

I understand it and reconsider this commit.
Thank you for reviewing this.

Seunghui Lee.