RE: [LINUX PATCH 4/5] Documentation: mmc: Updated the binding doc for Arasan SDHCI.

From: Lakshmi Sai Krishna Potthuri
Date: Wed Jan 20 2016 - 00:51:32 EST


Hi,

> -----Original Message-----
> From: Rob Herring [mailto:robh@xxxxxxxxxx]
> Sent: Tuesday, January 19, 2016 10:46 PM
> To: Lakshmi Sai Krishna Potthuri
> Cc: Michal Simek; Soren Brinkmann; Ulf Hansson; Kevin Hao; Emil P. Lenchak;
> Tobias Klauser; Sudeep Holla; Adrian Hunter; Jisheng Zhang; Ivan T. Ivanov;
> Scott Branden; Vincent Yang; Haibo Chen; Marek Vasut;
> ludovic.desroches@xxxxxxxxx; Pawel Moll; Mark Rutland; Ian Campbell;
> Kumar Gala; Suman Tripathi; Shawn Lin; devicetree@xxxxxxxxxxxxxxx; Harini
> Katakam; linux-mmc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> Lakshmi Sai Krishna Potthuri; Anirudha Sarangi; Punnaiah Choudary Kalluri;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [LINUX PATCH 4/5] Documentation: mmc: Updated the binding
> doc for Arasan SDHCI.
>
> On Tue, Jan 19, 2016 at 07:47:34PM +0530, P L Sai Krishna wrote:
> > This patch adds broken-mmc-highspeed property to the binding doc for
> > Arasan SDHCI.
> >
> > Signed-off-by: P L Sai Krishna <lakshmis@xxxxxxxxxx>
> > ---
<snip>
> > -
> > + - broken-mmc-highspeed: Indicates to force
> > + the controller to use in standard speed.
>
> We already have the inverse of this with "cap-mmc-highspeed".
>
> The only potential problem is it will need to be added to existing DTs if you
> start disabling high speed by default. Maybe that's not an issue for users of
> the Arasan driver.
>

It might be an issue for other users.
I know that it will be an issue for older Xilinx SoC (Zynq), for ex.

> Otherwise, you should determine this with a more specific compatible string.
>

Since this feature might be broken on any SoC, I thought it would be
good to provide a dt property.
Using a compatibility string will offer no flexibility as per board or silicon.

Regards,
Harini


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