[PATCH] mmc: dt: Add 'broken-cd' DT binding

[Shawn Guo]

On Tue, Aug 21, 2012 at 10:48:43AM -0400, Chris Ball wrote:
> Aside: the bindings do not match the code.  The bindings document says
> to use "fsl,cd-internal", and imx51-babbage.dts does so -- but the code
> doesn't check for "fsl,cd-internal", it checks for "fsl,cd-controller":
> 
>         if (of_get_property(np, "fsl,cd-controller", NULL))
>                 boarddata->cd_type = ESDHC_CD_CONTROLLER;
> 
> The same confusion is present for fsl,wp-{controller,internal}.
> 
Thanks for spotting it.  I will submit a patch to fix binding doc and
dts.

> Ignoring that, these bindings are similar, but not the same -- imx-esdhc
> only allows one of the cd_type cases to be true, so you either have
> cd-internal or you have cd-gpios:
> 
>         if (of_get_property(np, "fsl,cd-controller", NULL))
>                 boarddata->cd_type = ESDHC_CD_CONTROLLER;
> 
>         boarddata->cd_gpio = of_get_named_gpio(np, "cd-gpios", 0);
>         if (gpio_is_valid(boarddata->cd_gpio))
>                 boarddata->cd_type = ESDHC_CD_GPIO;
> 
> This differs from Thomas's binding -- he wants a way to say "the cd-gpio
> mentioned in cd-gpios is [internal/external] to the card's CD pin".
> 
> Rob Herring said:
> > This makes the most sense to me. However, I prefer broken-cd over
> > cd-internal. The binding should add properties for exceptions, not SDHCI
> > spec compliant implementations.
> 
> Agreed, I was going to say the same thing.  Putting it all together, it
> sounds like we want:
> 
> no extra properties:  the CD pin on the host just works.
> broken-cd:            the CD pin on the host is broken; use polling.
> cd-gpios:             the GPIO listed is the CD pin on the host being
>                       brought out directly to a GPIO.
> cd-external:          when used with cd-gpios, specifies that the GPIO
>                       in cd-gpios is external to the CD pin on the host.
> 
> cd-gpios and cd-external can be present on the same node.  if broken-cd
> is present, it must be the only one of these nodes used.
> 
> Shawn, I guess I'll leave it up to you on whether/when you'd like to
> move away from the "fsl," properties to the new common ones?
> 
Ok, I will move to the common one once it appears on your tree.

-- 
Regards,
Shawn