Hi,
Michael Ellerman <mich...@ellerman.id.au> wrote on 20.05.2010 03:34:08: > Subject: > > Re: [PATCH RT] ehea: make receive irq handler non-threaded (IRQF_NODELAY) > > On Wed, 2010-05-19 at 23:08 +0200, Thomas Gleixner wrote: > > On Wed, 19 May 2010, Thomas Gleixner wrote: > > > > I'm still not clear on why the ultimate solution wasn't to > have XICS report > > > > edge triggered as edge triggered. Probably some complexity of > the entire power > > > > stack that I am ignorant of. > > > > > > > > > Apart from the issue of loosing interrupts there is also thefact that > > > > > masking on the XICS requires an RTAS call which takes a global lock. > > > > > > Right, I'd love to avoid that but with real level interrupts we'd run > > > into an interrupt storm. Though another solution would be to issue the > > > EOI after the threaded handler finished, that'd work as well, but > > > needs testing. > > > > Thought more about that. The case at hand (ehea) is nasty: > > > > The driver does _NOT_ disable the rx interrupt in the card in the rx > > interrupt handler - for whatever reason. > > Yeah I saw that, but I don't know why it's written that way. Perhaps > Jan-Bernd or Doug will chime in and enlighten us? :) >From our perspective there is no need to disable interrupts for the RX side as the chip does not fire further interrupts until we tell the chip to do so for a particular queue. We have multiple receive queues with an own interrupt each so that the interrupts can arrive on multiple CPUs in parallel. Interrupts are enabled again when we leave the NAPI Poll function for the corresponding receive queue. Michael, does this answer your question? Regards, Jan-Bernd _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
