> > Aaron Young wrote: > >> On Mon, 26 Nov 2007 13:39:41 -0800 (PST) > >> Aaron Young <[EMAIL PROTECTED]> wrote: > >> > >> > >>> Konstantin, some comments: > >>> > >>> 3. Why can't you use the HID URB? Locking? Using the HID URB seems > >>> to work fine for OHCI and EHCI. This is the reason that > >>> seems to cause so much complication in your code. Back > >>> in the 2.4 timeframe, Intel did a UHCI KDB implementation > >>> that used the HID URB. Perhaps it would be useful to dig up that > >>> old code and compare it? I can possibly pass that code on to you > >>> if you want... > >>> > >>> Also, does enqueing two URBs for the same device cause any > >>> problems (is it "legal")? > >>> > >>> > >>> -Aaron > >>> > >>> > >>> > >> I explained it earlier: > >> http://oss.sgi.com/archives/kdb/2007-11/msg00003.html > >> > >> KDB Poll driver should not depend on USB kernel code because (in case > >> when KDB driver uses the same code with kernel USB driver) if CPU0 > >> executes kernel USB driver and, in the same time, CPU1 hits breakpoint, > >> CPU0 would be frozen in kernel USB driver. USB spinlocks would be > >> locked by CPU0, so KDB USB code couldn't get lock and deadlock would > >> occur. Or, if we don't use lock, kernel USB driver data can't be > >> corrupted. > >> > > > > Yes - you're right - it's *possible* to get into kdb while locks are > > held which, if timed just perfectly, could result in kdb crashing trying > > to walk lists, etc. This is also true of EHCI and OHCI (I think). > > I've never seen it happen, but it could in theory... > > > > I'm not sure it's worth it to rewrite all this code to cover this > > possibility, > > so what I might consider doing is just to check for the critical locks > > being > > held out of the poll functions and if so, give an error and punt > > (return -1) - i.e. the keyboard(s) for > > that HC will not be useable in this case. Much easier > > and probably sufficient for a debugger IMO. > > > > Jay, prepare for another patch for this! ;-) > > > > -Aaron > > > Aaron, I'm little bit confused . Are you going to integrate my UHCI > code to KDB?
No - I was just talking about fixing OHCI and EHCI (in the manner I described above)... --------------------------- Use http://oss.sgi.com/ecartis to modify your settings or to unsubscribe.
