From: =?utf-8?B?U8O2cmVu?= Brinkmann <soren.brinkmann@xilinx.com>
Subject: Re: arasan,sdhci.txt "compatibility" DT binding
Date: Wed, 3 Feb 2016 07:21:04 -0800
Message-ID: <20160203152104.GP4215@xsjsorenbubuntu>
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Sender: linux-mmc-owner@vger.kernel.org
To: Michal Simek <michal.simek@xilinx.com>
Cc: Mason <slash.tmp@free.fr>, Shawn Lin <shawn.lin@rock-chips.com>, linux-mmc <linux-mmc@vger.kernel.org>, Michal Simek <monstr@monstr.eu>, Anton Vorontsov <anton@enomsg.org>, Xiaobo Xie <x.xie@freescale.com>, Suman Tripathi <stripathi@apm.com>

On Wed, 2016-02-03 at 10:58:24 +0100, Michal Simek wrote:
> On 3.2.2016 09:31, Mason wrote:
> > On 03/02/2016 08:20, Michal Simek wrote:
> >=20
> >> Hi,
> >>
> >> On 3.2.2016 03:33, Shawn Lin wrote:
> >>> + Michal, S=C3=B6ren Brinkmann
> >>>
> >>> On 2016/2/2 17:49, Mason wrote:
> >>>> Hello everyone,
> >>>>
> >>>> Documentation/devicetree/bindings/mmc/arasan,sdhci.txt states:
> >>>>
> >>>> Required Properties:
> >>>>    - compatible: Compatibility string. Must be 'arasan,sdhci-8.9=
a' or
> >>>>                  'arasan,sdhci-4.9a' or 'arasan,sdhci-5.1'
> >>>>
> >>>> What do 8.9a, 4.9a, and 5.1 refer to?
> >>>>
> >>>
> >>> Good question.
> >>>
> >>> Michal told me that 8.9a and 4.9a came from Xilinx
> >>> databook which define their available arasan controller to be ver=
sion
> >>> 4.9a and 8.9a.
> >>
> >> Our version is coming from here.
> >> http://www.xilinx.com/support/documentation/user_guides/ug585-Zynq=
-7000-TRM.pdf
> >> page 28
> >>
> >> Datasheets from 2012 and 2010 doesn't look too recent and I expect=
 that
> >> Arasan did a lot of work from that time that's why I am not surpri=
sed
> >> that you are not able to see that versions.
> >=20
> > Hello Michal,
> >=20
> > I'm even more confused.
> >=20
> > Arasan's 2010-02-19 data sheet is titled
> > SD3.0 / SDIO3.0 / eMMC4.4 AHB Host Controller
> >=20
> > Page 28 of the Xilinx data sheet mentions
> > SD2.0 / SDIO2.0 / MMC3.31 AHB Host Controller
> > Version 8.9A_apr02nd_2010
> >=20
> > It does not make sense that Arasan would support SD3.0 in February,
> > then go back to SD 2.0 in April.
> >=20
> > I do note eMMC4.4 vs MMC3.31 =3D> perhaps these are two *different*
> > IP blocks?
> >=20
> > Do your data sheets come with revision history?
>=20
> I don't have datasheet for this IP in my hand that's why I can't chec=
k it.
> But I can't see any problem with it. Our zynq SoC supports SD2.0 and =
it
> was requirement at that time. Bugs can happen. Arasan fixed it and
> create new version.
> At the same time can have 3.0 versions but vendor is just decide not =
to
> use it for whatever reason.
>=20
> That's why timing of features and versions can upgrade any time and
> unfortunately bugs happen.

We have several Arasan data sheets here. The document names are:
"SD2.0 / SDIO2.0 / MMC3.31 AHB Userguide" and the revisions are 9.2a,
4.4a and 5.4a. I have the feeling that the document revisions have
been mistaken as the IP revision. I cannot find any other indicator
for the IP revision though. Does the IP have a way to discover its
revision?

	S=C3=B6ren