Re: [PATCHv3] ARM: socfpga: dts: Add support for SD/MMC

[Dinh Nguyen <dinguyen@altera.com>]

On Tue, 2013-08-13 at 14:10 -0600, Stephen Warren wrote:
> On 08/13/2013 01:58 PM, Dinh Nguyen wrote:
> > On Tue, 2013-08-13 at 13:52 -0600, Stephen Warren wrote:
> >> On 08/12/2013 09:49 AM, dinguyen@altera.com wrote:
> >>> From: Dinh Nguyen <dinguyen@altera.com>
> >>>
> >>> Add bindings for SD/MMC for SOCFPGA.
> >>> Add "syscon" to the "altr,sys-mgr" binding.
> 
> >>> diff --git a/arch/arm/boot/dts/socfpga.dtsi b/arch/arm/boot/dts/socfpga.dtsi
> >>
> >>>  		sysmgr@ffd08000 {
> >>> -				compatible = "altr,sys-mgr";
> >>> +				compatible = "altr,sys-mgr", "syscon";
> >>
> >> That seems like an unrelated change?
> > 
> > This patch is to enable SD/MMC for SOCFPGA. The "syscon" is needed in
> > dw_mmc-socfpga.c as the clock phases for the SD IP is controlled by
> > registers in "altr,sys-mgr".
> 
> But nothing in the dwmmc nodes refers to the syscon node, so how can the
> syscon driver possibly provide services to the MMC driver; the MMC
> driver won't be able to find it. I hope there's no back-door assumption
> that some syscon exists, and that there's only one of them...

In dw_mmc-socfpga.c:

priv->sysreg = syscon_regmap_lookup_by_compatible("altr,sys-mgr");

then, uses regmap_write() to set the correct values from
 "altr,dw-mshc-sdr-timing".

This was a suggestion from Arnd. It seems that this part of patch is
causing alot of confusion, I should just split the patches out?

Dinh

>