Re: [PATCH] mfd: ssbi: promote the driver to subsys level

From: Lee Jones <lee.jones@linaro.org>
To: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Samuel Ortiz <sameo@linux.intel.com>,
	Daniel Walker <dwalker@fifo99.com>,
	David Brown <davidb@codeaurora.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mfd: ssbi: promote the driver to subsys level
Date: Wed, 17 Sep 2014 15:25:19 -0700	[thread overview]
Message-ID: <20140917222519.GV30918@lee--X1> (raw)
In-Reply-To: <20140917164925.GO30918@lee--X1>

On Wed, 17 Sep 2014, Lee Jones wrote:

> On Wed, 17 Sep 2014, Srinivas Kandagatla wrote:
> 
> > On 17 Sep 2014 09:03, "Lee Jones" <lee.jones@linaro.org> wrote:
> > >
> > > On Wed, 17 Sep 2014, Srinivas Kandagatla wrote:
> > >
> > > > This patch promtes the driver to be at subsystem level as this driver
> > > > will be used by gpio controller drivers which inturn are used by many
> > > > platform drivers.
> > >
> > > Any reason why you're not using -EPROBE?
> > >
> > EPROBE is possible but it's going to add few more cycles to boot time.
> > 
> > As this driver is a very basic driver on which other drivers depend
> > ensuring the sequence would improve the boot time.
> 
> We only tend to promote drivers' init level as a last resort.  If
> -EPROBE_DEFER is possible, please use that instead.

To conclude for any casual/interested observers; I'd be willing to
accept the patch if you can provide some metrics that prove boot-time
is sufficiently increased as a result of using -EPROBE_DEFER.

> > > > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> > > > ---
> > > >  drivers/mfd/ssbi.c | 7 ++++++-
> > > >  1 file changed, 6 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/mfd/ssbi.c b/drivers/mfd/ssbi.c
> > > > index b78942e..4fbe02e 100644
> > > > --- a/drivers/mfd/ssbi.c
> > > > +++ b/drivers/mfd/ssbi.c
> > > > @@ -331,7 +331,12 @@ static struct platform_driver ssbi_driver = {
> > > >               .of_match_table = ssbi_match_table,
> > > >       },
> > > >  };
> > > > -module_platform_driver(ssbi_driver);
> > > > +
> > > > +static int ssbi_init(void)
> > > > +{
> > > > +     return platform_driver_register(&ssbi_driver);
> > > > +}
> > > > +subsys_initcall(ssbi_init);

Also, as a nasty side-effect of this patch, this module will no longer
be unloadable, which is probably not what you want.

> > > >  MODULE_LICENSE("GPL v2");
> > > >  MODULE_VERSION("1.0");

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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