Re: [PATCH 5/7] mmc: support sdhci-esdhc-imx as an OF device

[Rob Herring <robherring2@gmail.com>]

On 03/17/2011 03:22 PM, Grant Likely wrote:
> [cc'ing linux-mmc to continue this discussion]
>
> On Wed, Mar 16, 2011 at 10:39:16PM +0800, Shawn Guo wrote:
>> On Tue, Mar 15, 2011 at 01:59:26PM -0600, Grant Likely wrote:
>>> On Mon, Mar 14, 2011 at 10:25:57PM +0800, Shawn Guo wrote:
>>>> Signed-off-by: Shawn Guo<shawn.guo@linaro.org>
>>>
>>> dt support can be added directly to sdchi-pltfm.c drivers now.  There
>>> is no longer any need to use sdhci-of-core.c any more.  For an
>>> example, see the patch titled "of/tegra: add sdhci device tree
>>> handling" in my devicetree/test branch.
>>>
>> I mentioned this a little bit in the cover letter of the patch set
>> as below.
>>
>> "This patch set is to support sdhci-esdhc-imx as an OF device.  As
>> there is already powerpc based esdhc OF support, it chose to add OF
>> support for imx esdhc driver in a different way from what sdhci-tegra
>> did."
>
> I should read your descriptions more carefully.  :-)
>
>> The tegra approach you made was one of the two options I had, and I
>> happened to love the another more, as it consolidates the eSDHC OF
>> driver for Freescale MPCxxx and i.MX family.
>
> Heh, I don't dispute the value of merging code.  However, with this
> approach it means that DT and non-DT imx platforms will be using
> different drivers for the same device.  Given the choices, I'd
> rather see the imx driver used in both DT and non-DT situations
> instead of sharing code with the powerpc version.  I've learnt the
> hard way that it is just too painful having two drivers for the same
> hardware; particularly when the only difference is the method used to
> probe them.
>
> Actually, what I'd *really* rather see is the powerpc code migrated
> over to sdhci_pltfm.c, and then have the imx compatible value added to
> it.  I'll make sure to get some help from the Freescale powerpc folks
> to test any patch you produce to that end.

Based on past experience, there will be differences between imx and ppc 
h/w even though it is the "same" block.

Rob