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SubjectRe: [PATCH] USB: ftdi_sio: Remove tty->low_latency.
On Thu, Sep 24, 2009 at 08:21:07PM +0100, Alan Cox wrote:
> On Thu, 24 Sep 2009 21:03:47 +0200
> Oliver Neukum <oliver@neukum.org> wrote:

> > Am Donnerstag, 24. September 2009 17:40:23 schrieb Johan Hovold:
> > > Is there a reason why this was not fixed in ftdi_sio (and whiteheat?)
> > > along with the other drivers?

> > No good reason. They escaped my grep pattern. Mea culpa.

> ftdi_sio is correct with low_latency set as it uses a work queue to
> process the packets received.

AFAICT it only uses the work queue if tty_buffer_request_room fails to
allocate enough space. This being the exception, the completion
handler normally processes the packets in interrupt context and this is
where I get my lockdep traces (and it happens every time I hit the echo
or throttle paths).

/Johan



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