Messages in this thread | | | Date | Fri, 25 Sep 2009 19:46:51 +0200 | From | Michael Trimarchi <> | Subject | Re: [PATCH] USB: ftdi_sio: Remove tty->low_latency. |
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Johan Hovold wrote: > 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). > Hi,
Using two urb, double buffering and schedule a tasklet to complete the the reading phase. The usb will use the other free urb during receiving process. I think remove tty_latency is not a good fix.
Michael > /Johan > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > >
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