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From:   "Y.b. Lu" <yangbo.lu@nxp.com>
To:     Michael Walle <michael@walle.cc>
CC:     Vladimir Oltean <vladimir.oltean@nxp.com>,
        Shawn Guo <shawnguo@kernel.org>, Leo Li <leoyang.li@nxp.com>,
        Rob Herring <robh+dt@kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Ashish Kumar <ashish.kumar@nxp.com>
Subject: RE: [PATCH] arm64: dts: ls1028a: make the eMMC and SD card
 controllers use fixed indices
Thread-Topic: [PATCH] arm64: dts: ls1028a: make the eMMC and SD card
 controllers use fixed indices
Thread-Index: AQHWvovBvcqJCTixR025fdiTeTkR06nQRXqQgAB88ACABimgIIAAB1IAgAAEgOA=
Date:   Tue, 24 Nov 2020 08:47:42 +0000
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Hi Michael,

> -----Original Message-----
> From: Michael Walle <michael@walle.cc>
> Sent: Tuesday, November 24, 2020 4:03 PM
> To: Y.b. Lu <yangbo.lu@nxp.com>
> Cc: Vladimir Oltean <vladimir.oltean@nxp.com>; Shawn Guo
> <shawnguo@kernel.org>; Leo Li <leoyang.li@nxp.com>; Rob Herring
> <robh+dt@kernel.org>; linux-arm-kernel@lists.infradead.org;
> devicetree@vger.kernel.org; Adrian Hunter <adrian.hunter@intel.com>; Ulf
> Hansson <ulf.hansson@linaro.org>; linux-mmc@vger.kernel.org;
> linux-kernel@vger.kernel.org; Ashish Kumar <ashish.kumar@nxp.com>
> Subject: Re: [PATCH] arm64: dts: ls1028a: make the eMMC and SD card
> controllers use fixed indices
>=20
> Am 2020-11-24 08:41, schrieb Y.b. Lu:
> > Hi Vladimir,
> >
> >> -----Original Message-----
> >> From: Vladimir Oltean <vladimir.oltean@nxp.com>
> >> Sent: Friday, November 20, 2020 5:30 PM
> >> To: Y.b. Lu <yangbo.lu@nxp.com>
> >> Cc: Shawn Guo <shawnguo@kernel.org>; Leo Li <leoyang.li@nxp.com>; Rob
> >> Herring <robh+dt@kernel.org>; linux-arm-kernel@lists.infradead.org;
> >> devicetree@vger.kernel.org; Adrian Hunter <adrian.hunter@intel.com>;
> >> Ulf
> >> Hansson <ulf.hansson@linaro.org>; linux-mmc@vger.kernel.org;
> >> linux-kernel@vger.kernel.org; Ashish Kumar <ashish.kumar@nxp.com>;
> >> Michael Walle <michael@walle.cc>
> >> Subject: Re: [PATCH] arm64: dts: ls1028a: make the eMMC and SD card
> >> controllers use fixed indices
> >>
> >> On Fri, Nov 20, 2020 at 02:04:02AM +0000, Y.b. Lu wrote:
> >> > Hi Vladimir,
> >> >
> >> > I have already upstreamed a patch for all affected layerscape boards=
.
> >> >
> >>
> https://eur01.safelinks.protection.outlook.com/?url=3Dhttps%3A%2F%2Fgit.k=
ern
> el.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fshawnguo%2Flinux.git%2
> Fcommit%2F&amp;data=3D04%7C01%7Cyangbo.lu%40nxp.com%7C498622ade
> e704fc0042008d8904f6184%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0
> %7C0%7C637418017917635725%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiM
> C4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000
> &amp;sdata=3DOciS3q%2BmP%2Bz4x1ewPHDigmUkgIZmBgUlRRTm4yaxB7s%3D
> &amp;reserved=3D0?
> >> h=3Dimx/dt64&id=3D342ab37ecaf8c1b10dd3ca9a1271db29a6af0705
> >> >
> >> > Please check whether it works for you.
> >>
> >> Thanks, one can tell that I haven't done my due diligence of checking
> >> Shawn's tree first. I'll cherry-pick that patch and carry on with my
> >> work.
> >>
> >> However, the fact still remains that Michael has expressed his opinion
> >> regarding mmcblk0 vs mmcblk1. Do you think that we could make the
> >> aliases a per-board option instead of per-SoC? Consider that there
> >> might
> >> even be boards that only use SD card. It would be strange for the
> >> block
> >> device in that case to be called /dev/mmcblk1.
> >
> > I don't think it's a problem in board dts to define board specific
> > thing, like re-defining alias, and disabling any IP it not using.
>=20
> First, why would you put it in the architecture include anyway? That
> is really board-specific. That is like you would say, we enable all
> devices and a board could potentially disable it. TBH it seems that
> this will fit your reference boards and you don't care about the
> other ones which uses that include.

In soc dtsi, this is giving default alias for two esdhc controllers. This i=
s not board specific.
That's natural esdhc0 is mmc0 and esdhc1 is mmc1.

>=20
> And as Vladimir pointed out, what do you do if you just have the eMMC
> on the LS1028A. It will be mmcblk1 unless you do something like the
> following in the board dts:
>=20
> mmc0 =3D &esdhc;
> /delete-property/ mmc1;
>=20
> That is really cumbersome, isnt it?

The soc dtsi gives default alias to make esdhc0 as mmc0, and esdhc1 as mmc1=
, the use case just needs to consider which esdhc controller is used. That'=
s fixed index for it.
No matter how the board is designed, there are two esdhc controllers in soc=
. It's probed as mmc0 and mmc1.
It's use case that should choose the right mmc device. It is not the dts th=
at should be changed to suit use case.
If the board owner insists to change alias to make esdhc1 as mmc0, I think =
no problem. Just do it in board dts to override the default one.
Thanks.

>=20
> -michael