Message-ID: <1431509166.25254.12.camel@mtksdaap41>
Subject: Re: [PATCH 2/3] spi: mediatek: Add spi bus for Mediatek MT8173
From: Yingjoe Chen <yingjoe.chen@mediatek.com>
To: Mark Brown <broonie@kernel.org>
CC: leilk liu <leilk.liu@mediatek.com>, Mark Rutland <mark.rutland@arm.com>,
        <devicetree@vger.kernel.org>, <srv_heupstream@mediatek.com>,
        Pawel Moll <pawel.moll@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Hongzhou Yang <hongzhou.yang@mediatek.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        "Will Deacon" <will.deacon@arm.com>, <linux-kernel@vger.kernel.org>,
        <linux-spi@vger.kernel.org>, Rob Herring <robh+dt@kernel.org>,
        <linux-mediatek@lists.infradead.org>,
        Sascha Hauer <kernel@pengutronix.de>,
        Kumar Gala <galak@codeaurora.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Eddie Huang <eddie.huang@mediatek.com>,
        <linux-arm-kernel@lists.infradead.org>
Date: Wed, 13 May 2015 17:26:06 +0800
In-Reply-To: <20150512160540.GB3066@sirena.org.uk>
References: <1431075343-7887-1-git-send-email-leilk.liu@mediatek.com>
	 <1431075343-7887-3-git-send-email-leilk.liu@mediatek.com>
	 <20150508175306.GG2761@sirena.org.uk> <1431434356.2128.9.camel@mhfsdcap03>
	 <20150512160540.GB3066@sirena.org.uk>
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On Tue, 2015-05-12 at 17:05 +0100, Mark Brown wrote:
> On Tue, May 12, 2015 at 08:39:16PM +0800, leilk liu wrote:
<...>
> > > > +static const struct of_device_id mtk_spi_of_match[] = {
> > > > +	{ .compatible = "mediatek,mt6589-spi", .data = (void *)COMPAT_MT6589},
> > > > +	{ .compatible = "mediatek,mt8173-spi", .data = (void *)COMPAT_MT8173},
> > > > +	{}
> > > > +};
> > > > +MODULE_DEVICE_TABLE(of, mtk_spi_of_match);
> 
> > > There were three compatible strings listed in the DT binding but only
> > > two here.
> 
> > MT6589 and MT8135 is compatible; 
> > For MT8135 IC, it can use the follow way in dts to probe:
> >   compatible = "mediatek,mt8135-spi", 
> > 	       "mediatek,mt6589-spi";
> 
> > And I test it's ok on MT8135 platform. So I add struct of_device_id
> > mtk_spi_of_match like this in spi driver code.
> 
> You should list all the compatibles documented in the binding here, if
> some of them are the same just have them map to a single constant.

Hi Mark,

Just for clarification. If we want to add spi support for a new soc, say
mt8127, which we think is compatible to mt6589. Since it may turn out we
need special handling for this soc latter, it is suggested to write
compatible like this in mt8127.dtsi:

   compatible = "mediatek,mt8127-spi",
 	        "mediatek,mt6589-spi";

Device tree binding should list all possible compatible string in .dts,
so we'll have to add that to binding as well.

     - mediatek,mt6589-spi: for mt6589 platforms
+    - mediatek,mt8127-spi: for mt8127 platforms

Then we'll also need to add this to source code to reflect this.

	{ .compatible = "mediatek,mt6589-spi", .data = (void *)COMPAT_MT6589},
+	{ .compatible = "mediatek,mt8127-spi", .data = (void *)COMPAT_MT6589},

This seems to introduce lots of trivial patches just to add a compatible
device to me...

Joe.C


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