From mboxrd@z Thu Jan  1 00:00:00 1970
From: Lee Jones <lee.jones@linaro.org>
Subject: Re: [RFC 6/7] mfd: qcom-smd-rpm: Driver for the Qualcomm RPM over SMD
Date: Mon, 20 Oct 2014 08:22:11 +0100
Message-ID: <20141020072211.GC25349@x1>
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To: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Cc: Kumar Gala <galak@codeaurora.org>, Andy Gross <agross@codeaurora.org>, Arnd Bergmann <arnd@arndb.de>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Grant Likely <grant.likely@linaro.org>, Ian Campbell <ijc+devicetree@hellion.org.uk>, Liam Girdwood <lgirdwood@gmail.com>, Mark Brown <broonie@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Pawel Moll <pawel.moll@arm.com>, Rob Herring <robh+dt@kernel.org>, Samuel Ortiz <sameo@linux.intel.com>
List-Id: devicetree@vger.kernel.org

On Fri, 17 Oct 2014, Bjorn Andersson wrote:
> On Wed 08 Oct 01:40 PDT 2014, Lee Jones wrote:

[...]

> > > +static struct qcom_smd_driver qcom_smd_rpm_driver =3D {
> > > +	.probe =3D qcom_smd_rpm_probe,
> > > +	.remove =3D qcom_smd_rpm_remove,
> > > +	.callback =3D qcom_smd_rpm_callback,
> > > +	.driver  =3D {
> > > +		.name  =3D "qcom_smd_rpm",
> > > +		.owner =3D THIS_MODULE,
> > > +		.of_match_table =3D qcom_smd_rpm_of_match,
> > > +	},
> > > +};
> > > +
> > > +module_qcom_smd_driver(qcom_smd_rpm_driver);
> >=20
> > I don't like this.  What's wrong with the existing platform driver
> > code?
> >=20
>=20
> I started off with having smd child devices as platform drivers and h=
ad some
> accessor functions to find the open handles that triggered the probe(=
) and
> register the callback with those. But this didn't feel very sane, so =
I did
> implemented a custom driver struct and probe prototype to simplify wr=
iting
> drivers.
>=20
> May I ask why you dislike this? This is how it's done in so many othe=
r places
> in the kernel...

I don't believe that's the case.  All owners of their own
module_*_driver() registration calls are busses (see below), whereas
'qcom_smd' is just a driver.  Things would soon get out of control if
we allowed every driver in the kernel to supply their own driver
registration information variants.

$ git grep "^module_.*_driver(" | \
  cut -d: -f2 | cut -d'(' -f1 | sort | uniq

module_acpi_driver
module_amba_driver
module_comedi_driver
module_comedi_pci_driver
module_comedi_pcmcia_driver
module_comedi_usb_driver
module_gameport_driver
module_hid_driver
module_i2c_driver
module_mcb_driver
module_mipi_dsi_driver
module_pci_driver
module_pcmcia_driver
module_platform_driver
module_serio_driver
module_spi_driver
module_spmi_driver
module_usb_composite_driver
module_usb_driver
module_usb_serial_driver
module_virtio_driver

--=20
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org =E2=94=82 Open source software for ARM SoCs
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