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    SubjectRe: [PATCH v3] uio/pdrv_genirq: Add OF support
    On Tue, Apr 19, 2011 at 6:37 AM, John Williams
    <> wrote:
    > On Tue, Apr 19, 2011 at 4:11 PM, Grant Likely <> wrote:
    >> On Tue, Apr 19, 2011 at 11:58:25AM +1000, John Williams wrote:
    >>> On Tue, Apr 19, 2011 at 2:06 AM, Wolfram Sang <> wrote:
    >>> > Hi,
    >>> >
    >>> >> For example with "uio" compatible string:
    >>> >> static const struct of_device_id __devinitconst uio_of_genirq_match[] = {
    >>> >>       { .compatible = "uio", },
    >>> >>       { /* empty for now */ },
    >>> >> };
    >>> >
    >>> > Please use a proper example with "vendor,device".
    >>> > (And after that it won't be empty anymore)
    >>> My vote is, and always has been 'generic-uio' :)
    >>> Putting some random vendor/device string in there is just nuts. Do you
    >>> really want a kernel patch every time some one binds their device to
    >>> it?
    >>> Or, is there no expectation that anybody would attempt to merge such a
    >>> pointless patch to begin with?
    >>> As we discussed at ELC, putting a real vendor/device in there is also
    >>> broken because all instances in the system wil bind to the generic
    >>> uio, which is not necessarily what is desired.
    >>> I know the arguments against the 'generic-uio' tag, but come on, let's
    >>> look at the lesser of two evils here!  I call BS on this DTS purity.
    >> Call it what you like, but the reasons are well founded.  The alternative
    >> that has been proposed which I am in agreement with is to investigate
    >> giving userspace the hook to tell the kernel at runtime which devices
    >> should be picked up by the uio driver.
    > OK, so let's talk about this interface.  As I see it, it must be able
    > to handle bind per-instance, not per compatibility.
    > For example, we make systems with multiple, identical timers.  One
    > will be used as the system timer, the others need to be (optionally)
    > bound to generic UIO.
    > Therefore, it's not OK to just do
    > echo "vendor,device" >> /sys/class/something/generic-uio/compatlist
    > or whatever, as this would bind all instances matching vendor,device.
    > So, the question I have is, how to handle bind per-instance?

    By manipulating a property on the device instance of course! :-)

    Something like: echo "generic-uio" >>

    >> In the mean time, explicitly modifying the match table is an okay
    >> compromise.
    > My mind is still boggling that in this day and age it could possibly
    > be preferred to modify code, instead of a data structure.  However,
    > clearly this is a lost cause!

    I don't think anybody wants this as a long term solution. It is
    merely a stop-gap so that development is not stalled while working out
    a real interface.

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      Last update: 2011-04-19 16:53    [W:0.027 / U:10.552 seconds]
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