From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1ILN2S-0000x0-Tc for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:52:12 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1ILN2R-0000w1-DG for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:52:11 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ILN2Q-0000vv-PS for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:52:10 -0400 Received: from nf-out-0910.google.com ([64.233.182.184]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1ILN2Q-0007KQ-7W for qemu-devel@nongnu.org; Wed, 15 Aug 2007 13:52:10 -0400 Received: by nf-out-0910.google.com with SMTP id 30so181nfu for ; Wed, 15 Aug 2007 10:52:09 -0700 (PDT) Message-ID: Date: Wed, 15 Aug 2007 20:52:08 +0300 From: "Blue Swirl" Subject: Re: [Qemu-devel] Re: Extending qemu_irq for reset signals In-Reply-To: <200708151842.17437.paul@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200708151822.56446.paul@codesourcery.com> <200708151842.17437.paul@codesourcery.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On 8/15/07, Paul Brook wrote: > On Wednesday 15 August 2007, Blue Swirl wrote: > > 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); > > I'm not so keen on that. It breaks the nice property of having the IRQ lines > owned by the receiver. I was thinking something like: > > struct DMAState { > qemu_irq device_reset; > }; > qemu_irq *dma_init() > { > struct DMAState * d = malloc(); > return &d->device_reset; > } > > void esp_init(qemu_irq *resetp) > { > ESPState *d = malloc(); > *reset = *qemu_irq_alloc(d, 1); > } > > void sun4m_init() > { > qemu_irq *p = dma_init(); > esp_init(p); > } Yes, that would work. I wasn't too happy about the change function either.