Re: [v6, 5/5] mmc: sdhci-of-esdhc: fix host version for T4240-R1.0-R2.0

[Arnd Bergmann <arnd@arndb.de>]

On Thursday 17 March 2016 12:01:01 Rob Herring wrote:
> On Mon, Mar 14, 2016 at 05:45:43PM +0000, Scott Wood wrote:

> > >> This makes the driver non-portable. Better identify the specific=

> > >> workarounds based on the compatible string for this device, or a=
dd a
> > >> boolean DT property for the quirk.
> > >>
> > >>    Arnd
> > >=20
> > > [Lu Yangbo-B47093] Hi Arnd, we did have a discussion about using =
DTS in v1 before.
> > > https://patchwork.kernel.org/patch/6834221/
> > >=20
> > > We don=E2=80=99t have a separate DTS file for each revision of an=
 SOC and if we did, we'd constantly have people using the wrong one.
> > > In addition, the device tree is stable ABI and errata are often d=
iscovered after device tree are deployed.
> > > See the link for details.
> > >=20
> > > So we decide to read SVR from the device-config/guts MMIO block o=
ther than using DTS.
> > > Thanks.
> >=20
> > Also note that this driver is already only for fsl-specific hardwar=
e,
> > and it will still work even if fsl_guts doesn't find anything to bi=
nd to
> > -- it just wouldn't be able to detect errata based on SVR in that c=
ase.
>=20
> IIRC, it is the same IP block as i.MX and Arnd's point is this won't=20=

> even compile on !PPC. It is things like this that prevent sharing the=
=20
> driver.

I think the first four patches take care of building for ARM,
but the problem remains if you want to enable COMPILE_TEST as
we need for certain automated checking.

> Dealing with Si revs is a common problem. We should have a=20
> common solution. There is soc_device for this purpose.

Exactly. The last time this came up, I think we agreed to implement a
helper using glob_match() on the soc_device strings. Unfortunately
this hasn't happened then, but I'd still prefer that over yet another
vendor-specific way of dealing with the generic issue.

=09Arnd