Re: [PATCH v3 2/5] dt-bindings: input/touchscreen: Add compatible for IST3038B

From: "Karel Balej" <karelb@gimli.ms.mff.cuni.cz>
To: "Markuss Broks" <markuss.broks@gmail.com>
Cc: "Conor Dooley" <conor.dooley@microchip.com>,
	"Dmitry Torokhov" <dmitry.torokhov@gmail.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Henrik Rydberg" <rydberg@bitmath.org>,
	linux-input@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Duje Mihanović" <duje.mihanovic@skole.hr>,
	~postmarketos/upstreaming@lists.sr.ht,
	phone-devel@vger.kernel.org, "Karel Balej" <balejk@matfyz.cz>,
	"Conor Dooley" <conor@kernel.org>
Subject: Re: [PATCH v3 2/5] dt-bindings: input/touchscreen: Add compatible for IST3038B
Date: Wed, 27 Dec 2023 12:55:57 +0100	[thread overview]
Message-ID: <CXZ3I4X6XODY.1PMT2LS10M50M@gimli.ms.mff.cuni.cz> (raw)
In-Reply-To: <20231209-casing-music-bded1c7b5475@spud>

Markuss,

On Sat Dec 9, 2023 at 11:58 AM CET, Conor Dooley wrote:
> On Sat, Dec 09, 2023 at 10:05:27AM +0100, Karel Balej wrote:
> > On Mon Dec 4, 2023 at 1:52 PM CET, Conor Dooley wrote:
> > > On Mon, Dec 04, 2023 at 02:40:44PM +0200, Markuss Broks wrote:
> > > > On 12/3/23 13:20, Conor Dooley wrote:
> > > > > On Sat, Dec 02, 2023 at 01:48:33PM +0100, Karel Balej wrote:
> > > > > > From: Markuss Broks <markuss.broks@gmail.com>
> > > > > > 
> > > > > > Imagis IST3038B is a variant (firmware?) of Imagis IST3038 IC,
> > > > > > add the compatible for it to the IST3038C bindings.
> > > > > This one is better, but would be well served by mentioning what
> > > > > specifically is different (register addresses or firmware commands?)
> > > > 
> > > > I don't think anyone knows this other than Imagis itself. I would guess it's
> > > > different hardware, since register addresses are indeed different, but on
> > > > the other hand, there is a possibility that firmware on the MCU could be
> > > > responding to those commands. I suppose "... IST3038B is a hardware variant
> > > > of ... IST3038" would be more correct.
> > >
> > > Only Imagis might know the specifics, but you (plural) have made driver
> > > changes so you know what is different in terms of the programming model.
> > > I'm just asking for you to mention how the programming model varies in
> > > the commit message. Otherwise I can't know whether you should have added
> > > a fallback compatible, without going and reading your driver change. The
> > > commit message for the bindings should stand on its own merit in that
> > > regard.
> > > "Variant" alone does not suffice, as many variants of devices have a
> > > compatible programming model, be that for a subset of features or
> > > complete compatibility.
> > >
> > > > The reason why I think it could be firmware-defined is because we have a lot
> > > > of variants (30xxA, 30xxB, 30xxC, plain 30xx), and the numbers usually mean
> > > > feature level/completeness, e.g. some don't support the touch pressure or
> > > > touchkeys, and we don't know what A/B/C/none means.
> > >
> > > Ultimately whether it is due to firmware or the hardware isn't
> > > particular important, just mention what is incompatibly different.
> > 
> > I propose to update the commit description as such:
> > 
> > 	Imagis IST3038B is a variant (firmware?) of Imagis IST3038 IC
> > 	differing from IST3038C in its register interface. Add the
> > 	compatible for it to the IST3038C bindings.

is this change OK with you?

>
>
> SGTM. You can add
> Acked-by: Conor Dooley <conor.dooley@microchip.com>
> with that commit message update.
>
> Thanks,
> Conor.

Kind regards,
K. B.