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    SubjectRe: Threaded interrupts for synaptic touchscreen in HTC dream


    On Tue, 21 Jul 2009, Dmitry Torokhov wrote:

    > On Tue, Jul 21, 2009 at 10:30:26PM +0200, Thomas Gleixner wrote:
    > > On Tue, 21 Jul 2009, Dmitry Torokhov wrote:
    > >
    > > > On Tue, Jul 21, 2009 at 01:49:33PM +0100, Mark Brown wrote:
    > > > > On Tue, Jul 21, 2009 at 06:00:07PM +0530, Trilok Soni wrote:
    > > > >
    > > > > > Hopefully, this thread can give all details about threaded irq discussion.
    > > > >
    > > > > > http://lkml.org/lkml/2009/2/27/255
    > > > >
    > > > > Yes, I'm aware of that - I read it at the time. It seemed to peter out
    > > > > without any satisfactory solution, unfortunately. There's two separate
    > > > > issues here:
    > > > >
    > > > > - Ordinary devices on interrupt driven or slow buses like I2C. These
    > > > > need something along the lines of request_threaded_irq() that's allows
    > > > > them to schedule the main IRQ handler outside hardirq context so
    > > > > that they can interact with the device. They need to do something in
    > > > > hardirq context to disable the interrupt if it's level triggered but
    > > > > most of the time the only option they've got is to disable the IRQ
    > > > > and reenable it when the worker thread is done. This is the issue
    > > > > here.
    > >
    > > There is already a sane solution to the problem:
    > >
    > > See http://lkml.org/lkml/2009/7/17/174
    > >
    > > > > My immediate thought when I noticed this was that we should probably
    > > > > fix request_threaded_irq() so that it's useful for them; I'd been
    > > > > intending to do some digging and try to understand why it is
    > > > > currently implemented as it is.
    > >
    > > What's to fix there ?
    > >
    >
    > duisable_irq_nosync() in the hard interrupt handler stops the thread
    > handler from running. Unfortunately there are devices where it is the
    > only thing we can do in the hard interrupt.

    Again:

    There is already a sane solution to the problem:

    See http://lkml.org/lkml/2009/7/17/174

    Thanks,

    tglx


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