Subject: Re: ARC dw-mshc binding compat string
To: Marek Vasut <marex@denx.de>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
References: <56F66121.8050507@denx.de> <56F6C639.5000301@mentor.com>
 <56F6C71B.6070002@denx.de>
CC: <linux-kernel@vger.kernel.org>, Rob Herring <robh+dt@kernel.org>,
        Alexey Brodkin <abrodkin@synopsys.com>
From: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Message-ID: <56F6CC68.5040408@mentor.com>
Date: Sat, 26 Mar 2016 19:52:40 +0200
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Hi Marek,

On 26.03.2016 19:30, Marek Vasut wrote:
> On 03/26/2016 06:26 PM, Vladimir Zapolskiy wrote:
>> On 26.03.2016 12:14, Marek Vasut wrote:
>>> Hi!
>>>
>>> I noticed that arch/arc/boot/dts/axs10x_mb.dtsi uses "altr," prefix in
>>> the DT compatible string:
>>>
>>> mmc@0x15000 {
>>>         compatible = "altr,socfpga-dw-mshc";
>>>         reg = < 0x15000 0x400 >;
>>>         num-slots = < 1 >;
>>>         fifo-depth = < 16 >;
>>>         card-detect-delay = < 200 >;
>>>         clocks = <&apbclk>, <&mmcclk>;
>>>         clock-names = "biu", "ciu";
>>>         interrupts = < 7 >;
>>>         bus-width = < 4 >;
>>> };
>>>
>>> I don't think this is OK, since ARC is unrelated to Altera, which is
>>> what the "altr," prefix stands for. I think the socfpga-dw-mshc shim
>>> should be extended with another compatibility string, something like
>>> "snps,arc-dw-mshc" and the axs10x_mb.dtsi should be adjusted
>>> accordingly. What do you think ?
>>>
>>
>> There is "snps,dw-mshc" described in
>> Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt and supported by
>> dw_mmc host controller driver.
> 
> Thanks, that's even better.
> 
> btw what do you think of using altr, prefix on non-altera system, that
> doesn't seem ok, right ?

according to ePAPR the prefix should represent a device (IP block here
I believe) manufacturer, so it should be okay to use "altr" prefix on
non-Altera system, if Altera provides  another hardware vendor with
some own IP block.

That said, I would rather prefer to see "snps,dw-mshc" prefix on description
of an MMC controller found on SoCFPGA series, "altr,socfpga-dw-mshc" seems
to be redundant.

--
With best wishes,
Vladimir