From: "Blue Swirl" <blauwirbel@gmail.com>
To: Paul Brook <paul@codesourcery.com>
Cc: qemu-devel <qemu-devel@nongnu.org>
Subject: [Qemu-devel] Re: Extending qemu_irq for reset signals
Date: Wed, 15 Aug 2007 20:35:41 +0300 [thread overview]
Message-ID: <f43fc5580708151035i416c6e2h1acc7ed15dbc62d4@mail.gmail.com> (raw)
In-Reply-To: <200708151822.56446.paul@codesourcery.com>
On 8/15/07, Paul Brook <paul@codesourcery.com> 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.
next prev parent reply other threads:[~2007-08-15 17:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-15 16:13 [Qemu-devel] Extending qemu_irq for reset signals Blue Swirl
2007-08-15 16:34 ` [Qemu-devel] " Paul Brook
2007-08-15 16:53 ` Blue Swirl
2007-08-15 17:21 ` Paul Brook
2007-08-15 17:22 ` Paul Brook
2007-08-15 17:35 ` Blue Swirl [this message]
2007-08-15 17:42 ` Paul Brook
2007-08-15 17:52 ` Blue Swirl
2007-08-15 19:33 ` Blue Swirl
2007-08-15 19:44 ` Paul Brook
2007-08-15 17:47 ` Blue Swirl
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=f43fc5580708151035i416c6e2h1acc7ed15dbc62d4@mail.gmail.com \
--to=blauwirbel@gmail.com \
--cc=paul@codesourcery.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).