Message-ID: <4FCE07EE.40003@pengutronix.de>
Date: Tue, 05 Jun 2012 15:21:50 +0200
From: Marc Kleine-Budde <mkl@pengutronix.de>
Organization: Pengutronix e.K.
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120327 Thunderbird/11.0.1
MIME-Version: 1.0
To: Alessandro Rubini <rubini@gnudd.com>
CC: bhupesh.sharma@st.com, federico.vaga@gmail.com, alan@lxorguk.ukuu.org.uk,
        wg@grandegger.com, giancarlo.asnaghi@st.com, alan@linux.intel.com,
        linux-can@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] c_can_pci: generic module for c_can on PCI
References: <D5ECB3C7A6F99444980976A8C6D896384FA5EC4DFC@EAPEX1MAIL1.st.com>  <4FC135C6.5030206@grandegger.com> <1677842.Pq7naXsvrI@harkonnen>  <D5ECB3C7A6F99444980976A8C6D896384FA5EC4B37@EAPEX1MAIL1.st.com>  <3650428.HarNR9HfNF@harkonnen> <20120605131337.GA15432@mail.gnudd.com>
In-Reply-To: <20120605131337.GA15432@mail.gnudd.com>
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On 06/05/2012 03:13 PM, Alessandro Rubini wrote:
>>> My implementation is align to 32, but I'm trying to make a generic PC=
I
>>> wrapper (some other could be aligned to 16)
> =20
>> So it means your implementation is also flaky and you are probably
>> wasting HW memory space while integrating the Bosch C_CAN module in
>> your SoC :)
>=20
> Then I may say _your_ implementation is flaky because it wastes one
> bit in the address decoder and a lot of logic gates in the data
> bus. It's normal to align registers at 32 bits, as it's simpler and
> faster.  Most SoCs have only 32-bit aligned registers, for a reason.
>=20
>> I am not a big fan of adding platform specific flakes in any core
>> file, that why we keep the platform file separate from the core
>> ones.
>=20
> A number of other drivers have a shift parameter, because it's very
> common for the hardware integrator to feel free to choose the easiest
> wiring for the device.  The choice to keep the platform driver
> separate from the core driver only adds complication in my opinion:
> you need to export 4 symbols and yhen every user must duplicate code
> (like federico is replicating theplatform driver in the pci driver).
>=20
> I'd really prefer to have the core driver be a platform driver, and
> the others just add platform data to describe how it is wired. That's
> actually the reason why the platform bus exists.
>=20
>> But I will left Marc and Wolfgang to further comment on the same.
>=20
> I agree: let them decide.

I personally like the "pci device sets up a platform device" idea.

My question is, is this considered being a good practise?

Marc

--=20
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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