linux-kernel - Re: [PATCH 1/6] mailbox: add support for doorbell/signal mode controllers

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Message-ID: <20190604090123.GC23250@e107533-lin.cambridge.arm.com>
Date:   Tue, 4 Jun 2019 10:01:23 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Jassi Brar <jassisinghbrar@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Arnd Bergmann <arnd@...db.de>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Cristian Marussi <cristian.marussi@....com>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH 1/6] mailbox: add support for doorbell/signal mode
 controllers

On Mon, Jun 03, 2019 at 04:51:05PM -0500, Jassi Brar wrote:
> On Fri, May 31, 2019 at 9:33 AM Sudeep Holla <sudeep.holla@....com> wrote:
> 
> > diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
> > index 38d9df3fb199..e26a079f8223 100644
> > --- a/drivers/mailbox/mailbox.c
> > +++ b/drivers/mailbox/mailbox.c
> > @@ -77,7 +77,10 @@ static void msg_submit(struct mbox_chan *chan)
> >         if (chan->cl->tx_prepare)
> >                 chan->cl->tx_prepare(chan->cl, data);
> >         /* Try to submit a message to the MBOX controller */
> > -       err = chan->mbox->ops->send_data(chan, data);
> > +       if (chan->mbox->ops->send_data)
> > +               err = chan->mbox->ops->send_data(chan, data);
> > +       else
> > +               err = chan->mbox->ops->send_signal(chan);
> >         if (!err) {
> >                 chan->active_req = data;
> >                 chan->msg_count--;
> >
> The  'void *data'  parameter in send_data() is controller specific.
> The doorbell controllers should simply ignore that.
> 
> So signal/doorbell controllers are already supported fine. See
> drivers/mailbox/tegra-hsp.c for example.
>

Agreed, I did have that. But then I thought this API makes it even
clearer to the users that no data is expected. I am fine either way.

--
Regards,
Sudeep