[rt2x00-users] [RFC] rt2x00: Use tasklets for rt2x00usb

Helmut Schaa helmut.schaa at googlemail.com
Thu Jul 22 20:11:16 AEST 2010


Am Donnerstag 22 Juli 2010 schrieb Ivo Van Doorn:
> On Thu, Jul 22, 2010 at 9:19 AM, Helmut Schaa
> <helmut.schaa at googlemail.com> wrote:
> > Am Donnerstag 22 Juli 2010 schrieb Ivo Van Doorn:
> >> On Thu, Jul 22, 2010 at 8:53 AM, Helmut Schaa
> >> <helmut.schaa at googlemail.com> wrote:
> >> > Am Donnerstag 22 Juli 2010 schrieb Mark Asselstine:
> >> >> On Wed, Jul 21, 2010 at 6:32 PM, Ivo van Doorn <ivdoorn at gmail.com> wrote:
> >> >> > This updates the rt2x00usb driver to use tasklets for handling interrupts.
> >> >> > This simplifies the code in rt2x00lib since it no longer needs to check if the
> >> >> > device is USB or PCI to decide which mac80211 function should be used.
> >> >> >
> >> >> > This patch is work in progress, but I would to hear if there are any comments
> >> >> > on the approach taken.
> >> >> >
> >> >> > Signed-off-by: Ivo van Doorn <IvDoorn at gmail.com>
> >> >> > ---
> >> >>
> >> >> Ivo,  I know it has been far too long since I have done any work on
> >> >> this project and I am far from an expert so feel free hit the delete
> >> >> key... that being said. Tasklets are used less and less in the kernel
> >> >> as there are now other mechanisms which offer the same flexibility.
> >> >> Seeing this trend makes me feel rt2x00 is moving in the opposite
> >> >> direction. Have you looked at threaded interrupts (which are now in
> >> >> mainline) as an alternative? If I can get my development environment
> >> >> setup quickly I will try to do better then these few words and
> >> >> actually attempt an implementation if you think it is worth it.
> >> >
> >> > I agree. We switched all rt2x00 PCI drivers to use threaded interrupts
> >> > already. However, since the USB versions don't have something like an
> >> > interrupt handler I don't know how we could move the rx/tx handling
> >> > into process context without introducing delays (for example when using a
> >> > workqueue) and concurrency.
> >>
> >> The reason why I made the switch was in preparation for a different patch,
> >> which actually needs a short delay between the URB callback function and
> >> the processing of the data. And a side-benefit is that it manages to clean some
> >> stuff up in the TX/RX processing which is also nice. :)
> >
> > Ok, understood. I don't know what you're working on right now ;)
> 
> Oh, lets say that I am working on one of your ideas regarding rt2800usb
> and rate control mechanisms :P

Cool!

> > but the
> > tasklet approach should be fine (in regard to the mac80211 interaction at
> > least).
> 
> Well I just did some testing and rt2800usb needs to use a mutex, so
> tasklets aren't the right tool (Doh!). I'll convert it to the workqueue :)

Hmm, hopefully the workqueue doesn't delay too much.

Helmut





More information about the users mailing list