Received-SPF: pass (google.com: domain of linux-kernel+bounces-68543-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Date: Fri, 16 Feb 2024 11:47:03 +0000
From: Conor Dooley <conor.dooley@microchip.com>
To: Julien Panis <jpanis@baylibre.com>
CC: Conor Dooley <conor@kernel.org>, Kevin Hilman <khilman@kernel.org>,
	Bhargav Raviprakash <bhargav.r@ltts.com>, <arnd@arndb.de>,
	<broonie@kernel.org>, <conor+dt@kernel.org>, <devicetree@vger.kernel.org>,
	<gregkh@linuxfoundation.org>, <kristo@kernel.org>,
	<krzysztof.kozlowski+dt@linaro.org>, <lee@kernel.org>, <lgirdwood@gmail.com>,
	<linus.walleij@linaro.org>, <linux-arm-kernel@lists.infradead.org>,
	<linux-gpio@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<m.nirmaladevi@ltts.com>, <nm@ti.com>, <robh+dt@kernel.org>,
	<vigneshr@ti.com>
Subject: Re: [RESEND PATCH v1 03/13] dt-bindings: mfd: ti,tps6594: Add TI
 TPS65224 PMIC
Message-ID: <20240216-chimp-endowment-e4c241e8e466@wendy>
References: <20240209-blitz-fidgety-78469aa80d6d@spud>
 <20240214093106.86483-1-bhargav.r@ltts.com>
 <20240214-galley-dweller-1e9872229d80@spud>
 <7hil2r5556.fsf@baylibre.com>
 <20240214-depraved-unfunded-3f0b3d6bf3e2@spud>
 <e13627e2-9d8f-437d-afe4-d8bfcade2f6a@baylibre.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha256;
	protocol="application/pgp-signature"; boundary="zk2oXzKpSp9IbgEb"
Content-Disposition: inline
In-Reply-To: <e13627e2-9d8f-437d-afe4-d8bfcade2f6a@baylibre.com>

--zk2oXzKpSp9IbgEb
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Fri, Feb 16, 2024 at 10:08:03AM +0100, Julien Panis wrote:
> On 2/14/24 18:45, Conor Dooley wrote:
> > On Wed, Feb 14, 2024 at 09:26:13AM -0800, Kevin Hilman wrote:
> > > Conor Dooley <conor@kernel.org> writes:
> > > > On Wed, Feb 14, 2024 at 03:01:06PM +0530, Bhargav Raviprakash wrote:
> > > > > On Fri 2/9/2024 10:41 PM, Conor Dooley wrote:
> > > > > > On Thu, Feb 08, 2024 at 04:23:33PM +0530, Bhargav Raviprakash w=
rote:
> > > > > > > TPS65224 is a Power Management IC with 4 Buck regulators and =
3 LDO
> > > > > > > regulators, it includes additional features like GPIOs, watch=
dog, ESMs
> > > > > > > (Error Signal Monitor), and PFSM (Pre-configurable Finite Sta=
te Machine)
> > > > > > > managing the state of the device.
> > > > > > > TPS6594 and TPS65224 have significant functional overlap.
> > > > > > What does "significant functional overlap" mean? Does one imple=
ment a
> > > > > > compatible subset of the other? I assume the answer is no, give=
n there
> > > > > > seems to be some core looking registers at different addresses.
> > > > > The intention behind =E2=80=9Csignificant functional overlap=E2=
=80=9D was meant to
> > > > > indicate a lot of the features between TPS6594 and TPS65224 overl=
ap,
> > > > > while there are some features specific to TPS65224.
> > > > > There is compatibility between the PMIC register maps, I2C, PFSM,
> > > > > and other drivers even though there are some core registers at
> > > > > different addresses.
> > > > >=20
> > > > > Would it be more appropriate to say the 2 devices are compatible =
and have
> > > > > sufficient feature overlap rather than significant functional ove=
rlap?
> > > > If core registers are at different addresses, then it is unlikely t=
hat
> > > > these devices are compatible.
> > > That's not necessarily true.  Hardware designers can sometimes be
> > > creative. :)
> > Hence "unlikely" in my mail :)
>=20
> For tps6594 and tps65224, some core registers are at different adresses
> indeed, but the code is the same for both MFD I2C/SPI entry points. As an
> example, the way CRC is enabled is exactly the same, even if the bit that
> must be set belongs to different registers. tps65224 has more resources a=
nd
> it's as if HW designers had had to re-organize the way bits are distribut=
ed
> among the registers (due to a lack of space, so to speak).
>=20
> That said, if we consider that these devices are not compatible, what doe=
s it
> imply concretely for the next version ? Does that mean that:
> 1) Only a new binding must be created, even if MFD drivers and most of ch=
ild
> drivers will be re-used ? (then the binding would simply be duplicated, b=
ut
> the drivers would not)
> 2) A new binding and new MFD drivers must be created, even if most of chi=
ld
> drivers will be re-used ? (then the binding and MFD drivers would simply =
be
> duplicated, but the child drivers would not)
> 3) A new binding and new drivers (MFD and child devices) must be created ?
> 4) Anything else ?

If they're not compatible the next version of this patch does not need
to change, so option 4 I guess.


--zk2oXzKpSp9IbgEb
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZc9LNwAKCRB4tDGHoIJi
0pedAPwIn8EzGb7CK85veeqxTab48XHAJBFZX5GiGXdXq9JL9AD/Uz/cmlDaU22C
5UOMmufi3WxQg2fkU46lxarbGj0MvgQ=
=vBKa
-----END PGP SIGNATURE-----

--zk2oXzKpSp9IbgEb--