From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53312) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Sdh3r-0002br-9G for qemu-devel@nongnu.org; Sun, 10 Jun 2012 08:16:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Sdh3p-0006mW-Jm for qemu-devel@nongnu.org; Sun, 10 Jun 2012 08:16:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:20925) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Sdh3p-0006mP-BO for qemu-devel@nongnu.org; Sun, 10 Jun 2012 08:16:01 -0400 Date: Sun, 10 Jun 2012 15:16:29 +0300 From: "Michael S. Tsirkin" Message-ID: <20120610121628.GA7852@redhat.com> References: <73f236cab517fc5b2c2ba332e9efe2acbe727151.1338799936.git.jan.kiszka@siemens.com> <20120610094840.GC6250@redhat.com> <4FD47156.3020200@web.de> <20120610103352.GE6250@redhat.com> <4FD47A75.4020706@web.de> <20120610111149.GJ6250@redhat.com> <4FD48277.60704@web.de> <20120610113922.GO6250@redhat.com> <4FD48E70.3080406@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FD48E70.3080406@web.de> Subject: Re: [Qemu-devel] [PATCH 06/13] pci: Add INTx routing notifier List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Alex Williamson , qemu-devel On Sun, Jun 10, 2012 at 02:09:20PM +0200, Jan Kiszka wrote: > On 2012-06-10 13:39, Michael S. Tsirkin wrote: > > It's OK to use recursion but when done through a callback > > like this it's unreadable. > > Isn't the alternative poking into foreign bridge device states for their > secondary buses? pci_set_bus_intx_routing does this already. > > Also, you need to setup you cache after intx cache has been > > initialized, and you provide no clean way to do that. > > Once a PCI device is registered, the INTx route can be queried. So the > device user will call pci_device_route_intx_to_irq once (e.g. in the > device init function which is invoked afterward) to fill its cache and > receive a notification if an update is needed. I do not see why, and > specifically how you could query the route earlier or register a callback. Before pci_bus_irqs is called. Why is another question. > > > > One way to fix all this is call the notifier for devices, if set, from > > pci_set_bus_intx_routing. > > Then assume that intx to irq translations can be cached > > even though they aren't now. So you will need to invoke > > pci_set_bus_intx_routing on intx to irq mapping changes, > > and that fires the notifier for free. > > pci_set_bus_intx_routing is really only for the initial setup of the > static INTx pin routes. And this happens on > pci_bus_irqs/pci_register_bus, ie. triggered by the host bridge. By that > time, there can't be any notifier listeners - as there are no devices yet. > > Jan > What I am saying is we'll cache the final IRQ at some point. Pretend it's already that way so callers are ready for this. -- MST