From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1ILMmW-0004E2-HS for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:35:44 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1ILMmV-0004Au-Cy for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:35:43 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ILMmV-0004AM-4Q for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:35:43 -0400 Received: from nf-out-0910.google.com ([64.233.182.186]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1ILMmU-0003F3-NE for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:35:42 -0400 Received: by nf-out-0910.google.com with SMTP id 30so882008nfu for ; Wed, 15 Aug 2007 10:35:41 -0700 (PDT) Message-ID: Date: Wed, 15 Aug 2007 20:35:41 +0300 From: "Blue Swirl" In-Reply-To: <200708151822.56446.paul@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200708151821.17608.paul@codesourcery.com> <200708151822.56446.paul@codesourcery.com> Subject: [Qemu-devel] Re: Extending qemu_irq for reset signals Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paul Brook Cc: qemu-devel On 8/15/07, Paul Brook wrote: > On Wednesday 15 August 2007, Paul Brook wrote: > > > Okay, more explaining. This is the case where I'd want to use the > > > signal: DMA controller ("upstream") can reset the slave device (ESP or > > > Lance). DMA controller is created first and I also want to allocate > > > reset signals at that point. Later when ESP is created, it should be > > > possible to put ESP reset function and opaque data to the signal given > > > but this is not possible with current API. Currently the DMA data > > > would be passed to qemu_allocate_irqs. > > > > Ah, I see. The problem here is that you've got a cyclic dependency. For DMA > > operations the ESP is in charge, so it makes sense to create the > > subservient DMA device first. For the reset signals the DMA controller is > > in charge so ideally you create the ESP device first. Because the DMA > > interface is most complicated, it's probably takes precedence. > > > > I think you need to modify or use sparc32_dma_set_reset_data to take a > > qemu_irq rather than a callback and opaque argument. Alternatively you can > > move things around a bit and have the sun4m code do something similar. i.e. > > the ESP and lance devices return the reset lines, then the sun4m code pokes > > into the DMA device state. > > Oh, or you can pass a pointer to a qemu_irq from the DMA to the ESP and have > the ESP poke its reset object in there that way. That's what I had in mind. Should I just extend the API for example with /* Change the callback function and/or data */ void qemu_irq_change(qemu_irq irq, qemu_irq_handler handler, void *opaque); ? There is a small problem that DMA may not assert the reset signal before ESP gets the data in place. Usually devices perform reset when created.