From: Andres Salomon <dilinger-pFFUokh25LWsTnJN9+BGXg@public.gmane.org>
To: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: Samuel Ortiz <sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Mark Brown
<broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>,
khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org,
ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org,
Peter Korsgaard <jacmet-OfajU3CKLf1/SzgSGea1oA@public.gmane.org>,
Mauro Carvalho Chehab
<mchehab-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
David Brownell
<dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
Mocean Laboratories
<info-l7gf1WXxx3uGw+nKnLezzg@public.gmane.org>,
Greg Kroah-Hartman <gregkh-l3A5Bk7waGM@public.gmane.org>
Subject: Re: [PATCH 07/19] timberdale: mfd_cell is now implicitly available to drivers
Date: Fri, 1 Apr 2011 17:10:01 -0700 [thread overview]
Message-ID: <20110401171001.61283e2d@debxo> (raw)
In-Reply-To: <BANLkTi=bq=OGzXFp7qiBr7x_BnGOWf=DRQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Fri, 1 Apr 2011 17:58:44 -0600
Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> On Fri, Apr 1, 2011 at 5:52 PM, Samuel Ortiz <sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> wrote:
> > On Fri, Apr 01, 2011 at 11:56:35AM -0600, Grant Likely wrote:
> >> On Fri, Apr 1, 2011 at 11:47 AM, Andres Salomon
> >> <dilinger-pFFUokh25LWsTnJN9+BGXg@public.gmane.org> wrote:
> >> > On Fri, 1 Apr 2011 13:20:31 +0200
> >> > Samuel Ortiz <sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> wrote:
> >> >
> >> >> Hi Grant,
> >> >>
> >> >> On Thu, Mar 31, 2011 at 05:05:22PM -0600, Grant Likely wrote:
> >> > [...]
> >> >> > Gah. Not all devices instantiated via mfd will be an mfd
> >> >> > device, which means that the driver may very well expect an
> >> >> > *entirely different* platform_device pointer; which further
> >> >> > means a very high potential of incorrectly dereferenced
> >> >> > structures (as evidenced by a patch series that is not
> >> >> > bisectable). For instance, the xilinx ip cores are used by
> >> >> > more than just mfd.
> >> >> I agree. Since the vast majority of the MFD subdevices are MFD
> >> >> specific IPs, I overlooked that part. The impacted drivers are
> >> >> the timberdale and the DaVinci voice codec ones.
> >>
> >> Another option is you could do this for MFD devices:
> >>
> >> struct mfd_device {
> >> struct platform_devce pdev;
> >> struct mfd_cell *cell;
> >> };
> >>
> >> However, that requires that drivers using the mfd_cell will *never*
> >> get instantiated outside of the mfd infrastructure, and there is no
> >> way to protect against this so it is probably a bad idea.
> >>
> >> Or, mfd_cell could be added to platform_device directly which would
> >> *by far* be the safest option at the cost of every platform_device
> >> having a mostly unused mfd_cell pointer. Not a significant cost
> >> in my opinion.
> > I thought about this one, but I had the impression people would
> > want to kill me for adding an MFD specific pointer to
> > platform_device. I guess it's worth giving it a try since it would
> > be a simple and safe solution. I'll look at it later this weekend.
> >
> > Thanks for the input.
>
> [cc'ing gregkh because we're talking about modifying struct
> platform_device]
>
> I'll back you up on this one. It is a far better solution than the
> alternatives. At least with mfd, it covers a large set of devices. I
> think there is a strong argument for doing this. Or alternatively,
> the particular interesting fields from mfd_cell could be added to
> platform_device. What information do child devices need access to?
>
This was one of the things I was originally tempted to do (adding
mfd fields to platform_device). I didn't think it would fly.
I can look at this stuff or help out once I have a stable internet
connection and I'm all moved in to my new place (which should be
Wednesday).
next prev parent reply other threads:[~2011-04-02 0:10 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20110202195417.228e2656@queued.net>
[not found] ` <20110202195417.228e2656-pFFUokh25LWsTnJN9+BGXg@public.gmane.org>
2011-02-03 4:08 ` [PATCH 07/19] timberdale: mfd_cell is now implicitly available to drivers Andres Salomon
2011-03-31 23:05 ` Grant Likely
[not found] ` <20110331230522.GI437-e0URQFbLeQY2iJbIjFUEsiwD8/FfD2ys@public.gmane.org>
2011-04-01 11:20 ` Samuel Ortiz
2011-04-01 17:47 ` Andres Salomon
2011-04-01 17:56 ` Grant Likely
2011-04-01 18:00 ` Grant Likely
[not found] ` <BANLkTi=bCd_+f=EG-O=U5VH_ZNjFhxkziQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-04-01 23:52 ` Samuel Ortiz
2011-04-01 23:58 ` Grant Likely
[not found] ` <BANLkTi=bq=OGzXFp7qiBr7x_BnGOWf=DRQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-04-02 0:10 ` Andres Salomon [this message]
2011-04-04 10:03 ` Samuel Ortiz
2011-04-05 3:04 ` Grant Likely
2011-04-06 15:23 ` Samuel Ortiz
2011-04-06 15:58 ` Greg KH
2011-04-06 17:05 ` Samuel Ortiz
2011-04-06 17:16 ` Ben Hutchings
2011-04-06 17:51 ` Samuel Ortiz
2011-04-06 18:07 ` Ben Hutchings
2011-04-06 17:56 ` Greg KH
2011-04-06 18:25 ` Andres Salomon
2011-04-06 18:38 ` Greg KH
[not found] ` <20110406183854.GA10058-l3A5Bk7waGM@public.gmane.org>
2011-04-07 8:04 ` Grant Likely
2011-04-06 18:47 ` Samuel Ortiz
2011-04-06 18:59 ` Felipe Balbi
[not found] ` <20110406185902.GN25654-UiBtZHVXSwEVvW8u9ZQWYwjfymiNCTlR@public.gmane.org>
2011-04-06 22:09 ` Greg KH
2011-04-07 8:09 ` Felipe Balbi
2011-04-07 13:40 ` Samuel Ortiz
2011-04-07 14:35 ` Grant Likely
[not found] ` <20110407143515.GC26452-MrY2KI0G/OVr83L8+7iqerDks+cytr/Z@public.gmane.org>
2011-04-07 15:03 ` Samuel Ortiz
2011-04-07 18:06 ` Grant Likely
2011-04-07 16:24 ` Grant Likely
2011-04-01 18:26 ` Samuel Ortiz
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