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Date:   Fri, 30 Aug 2019 10:30:05 +0100
From:   Sudeep Holla <sudeep.holla@arm.com>
To:     Peng Fan <peng.fan@nxp.com>
Cc:     Jassi Brar <jassisinghbrar@gmail.com>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
        "andre.przywara@arm.com" <andre.przywara@arm.com>,
        "f.fainelli@gmail.com" <f.fainelli@gmail.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        dl-linux-imx <linux-imx@nxp.com>,
        Sudeep Holla <sudeep.holla@arm.com>
Subject: Re: [PATCH v5 1/2] dt-bindings: mailbox: add binding doc for the ARM
 SMC/HVC mailbox
Message-ID: <20190830093005.GA31297@bogus>
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On Fri, Aug 30, 2019 at 07:37:41AM +0000, Peng Fan wrote:
> Hi Jassi,
> > > I think there could be channel for TEE, and channel for Linux.
> > > For virtualization case, there could be dedicated channel for each VM.
> > >
> > I am talking from Linux pov. Functions 0xfe and 0xff above, can't both be
> > active at the same time, right?
>
> If I get your point correctly,
> On UP, both could not be active. On SMP, tx/rx could be both active, anyway
> this depends on secure firmware and Linux firmware design.
>

Just to confirm, we can't have SMC/HVC based Rx channel as there's no
*architectural* way to achieve it. So it can be based on some interrupt
from secure side and hence will be a *different* type of channel/controller.

Sorry to make this point repeatedly, but juts to be absolutely clear:
as it stands, SMC/HVC can be used only for Tx today.

--
Regards,
Sudeep