Re: bus_dmamap_sync() for USB

[David Young <dyoung%pobox.com@localhost>]

On Tue, Jun 24, 2008 at 08:55:51PM +0200, Manuel Bouyer wrote:
> On Tue, Jun 24, 2008 at 01:13:12PM -0500, David Young wrote:
> > What do you think the role of interrupt latency is?
> 
> The linked-list corruption is purely timing-related: the host has to 
> read/change it while the controller is reading/modifying it for it to happen.
> The controller looks at the linked list every microsecond (in other words,
> it's active every microsecond) If the interrupt handler runs fast enough
> (and is not heavily loaded, i.e. not talking to several devices/endpoints at
> once) it's likely to complete before the controller is active again.

Do you mean that there is still a known race condition in the code,
regardless of the DMA synchronization that you added?

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933 ext 24