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From:   Loys Ollivier <lollivier@baylibre.com>
To:     Johan Hovold <johan@kernel.org>
Cc:     Loys Ollivier <lollivier@baylibre.com>, devicetree@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        linux-kernel@vger.kernel.org, Kevin Hilman <khilman@baylibre.com>,
        linux-amlogic@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Subject: Re: [PATCH v2 2/4] dt-bindings: gnss: add mediatek binding
In-reply-to: <20190211083349.GU4686@localhost>
Date:   Mon, 11 Feb 2019 15:17:44 +0100
Message-ID: <86mun2v27r.fsf@baylibre.com>
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On Mon 11 Feb 2019 at 08:33, Johan Hovold <johan@kernel.org> wrote:

> On Mon, Jan 28, 2019 at 04:46:53PM +0100, Loys Ollivier wrote:
>> 
>> On Fri 25 Jan 2019 at 09:07, Johan Hovold wrote:
>> 
>> > On Thu, Jan 17, 2019 at 05:54:32PM +0100, Loys Ollivier wrote:
>> >> Add binding for Mediatek-based GNSS receivers.
>> >> 
>> >> Signed-off-by: Loys Ollivier <lollivier@baylibre.com>
>> >> ---
>> >> 
>> >> v2:
>> >> Renamed bindings from Globaltop/gtop to Mediatek/mtk.
>> >> Moved current-speed as an optional propertie.
>> >> Removed the status line in the example.
>> >> Added "mediatek,mt3339" compatible.
>
>> >> +++ b/Documentation/devicetree/bindings/gnss/mediatek.txt
>> >> @@ -0,0 +1,39 @@
>> >> +Mediatek-based GNSS Receiver DT binding
>> >> +
>> >> +Mediatek chipsets are used in GNSS-receiver modules produced by several
>> >> +vendors and can use UART, SPI or I2C interfaces.
>> >> +
>> >> +Please see Documentation/devicetree/bindings/gnss/gnss.txt for generic
>> >> +properties.
>> >> +
>> >> +Required properties:
>> >> +
>> >> +- compatible	: Must be one of
>> >> +
>> >> +			"globaltop,pa6h"
>> >> +			"mediatek,mt3339"
>> >
>> > I'm not sure it makes sense to add the GPS chip itself as it cannot be
>> > used stand-alone AFAIU, and either not way would require a lot more
>> > resources to be defined than what you add to this binding.
>> 
>> OK, I find it a bit confusing to have Mediatek bindings but no
>> compatible Mediatek SoCs.
>> But it is true that it can't be used stand-alone. I will remove this
>> reference and also remove it from the mtk.c driver code from this patch
>> serie.
>
>> >> +Required properties (I2C):
>> >> +- reg		: I2C slave address
>> >> +
>> >> +Required properties (SPI):
>> >> +- reg		: SPI chip select address
>> >
>> > While the mt3339 appears to support these interfaces, the globaltop one
>> > does not.
>> >
>> > Have you looked around for a small sample of mt3339-based receivers, to
>> > see whether anyone actually provides these?
>> 
>> Again I'm confused by the fact that it is the Mediatek bindings.
>> Hence why I have added it and why it was not present in the v1 that was
>> only for Globaltop.
>
> This is no different from the sirfstar driver for receivers based on
> those chipsets but manufactured by various other vendors.
>
Indeed.

>> I find it odd mentionning the chipset but not all its interfaces.
>> I will remove these sections and only list supported interfaces (i.e.
>> UART). Other interfaces can be added afterward if one finds a board that
>> provides them.
>
> Right, but please do look around for other receivers using this chipset
> so that we can make the binding generic enough to cover those as well
> (e.g. by choosing representative resource names).
>
OK will have a look.

> Johan


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-L