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    SubjectRe: [PATCH 07/19] timberdale: mfd_cell is now implicitly available to drivers
    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@queued.net> wrote:
    > > On Fri, 1 Apr 2011 13:20:31 +0200
    > > Samuel Ortiz <sameo@linux.intel.com> 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.

    Cheers,
    Samuel.

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