lkml.org 
[lkml]   [2009]   [Sep]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] USB: ftdi_sio: Remove tty->low_latency.
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/
>
>



\
 
 \ /
  Last update: 2009-09-25 19:51    [W:2.070 / U:0.488 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site