From mboxrd@z Thu Jan  1 00:00:00 1970
From: aisheng.dong@freescale.com (Dong Aisheng)
Date: Wed, 14 Mar 2012 15:26:04 +0800
Subject: [PATCH v1 2/5] mmc: mxs-mmc: add dt probe support
In-Reply-To: <201203140809.22676.marek.vasut@gmail.com>
References: <1331628428-24017-1-git-send-email-b29396@freescale.com>
 <201203140658.25854.marek.vasut@gmail.com>
 <20120314065512.GB25735@shlinux2.ap.freescale.net>
 <201203140809.22676.marek.vasut@gmail.com>
Message-ID: <20120314072603.GC8494@shlinux2.ap.freescale.net>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wed, Mar 14, 2012 at 08:09:22AM +0100, Marek Vasut wrote:
> Dear Dong Aisheng,
> 
> > On Wed, Mar 14, 2012 at 01:58:25PM +0800, Marek Vasut wrote:
> > > Dear Dong Aisheng,
> > > 
> > > > Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
> > 
> > ........
> > 
> > > > +static const struct of_device_id mxs_mmc_dt_ids[] = {
> > > > +	{ .compatible = "fsl,imx23-mmc", .data = NULL, },
> > > > +	{ .compatible = "fsl,imx28-mmc", .data = NULL, },
> > > 
> > > Do you really need two distinct ones here?
> > 
> > Hmm, my original purpose is to put soc difference data in .data
> > to remove cpu_is_* function calls in the driver later.
> > Do you think if any issue?
> > 
> 
> Well, what's the difference between the interfaces on mx233 and mx28? Is it 
> something that can't be encoded otherwise? I think they're not so different.
> 
Not much difference except the one register offset and ip version.
See:
#define SSP_VERSION_LATEST      4
#define ssp_is_old()            (host->version < SSP_VERSION_LATEST)
..
#define HW_SSP_VERSION (cpu_is_mx23() ? 0x110 : 0x130)
The ip version can be handled in driver, but for offset...
it depends on cpu_is_* macro.
Putting the HW_SSP_VERSION offset difference in .data can eliminate the need
of cpu_is_*.

Despite of that, since they're two devices,
i guess it's ok to put two compatible string there, right?
Or you thought just put one as below?
{ .compatible = "fsl,mxs-mmc", .data = NULL, },

Regards
Dong Aisheng