linux-kernel - Re: [PATCH V4 2/2] firmware: arm

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Message-ID: <20200306123442.GA47929@bogus>
Date:   Fri, 6 Mar 2020 14:23:13 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Peng Fan <peng.fan@....com>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
        dl-linux-imx <linux-imx@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH V4 2/2] firmware: arm_scmi: add smc/hvc transport

On Fri, Mar 06, 2020 at 08:07:19AM +0000, Peng Fan wrote:
> > Subject: Re: [PATCH V4 2/2] firmware: arm_scmi: add smc/hvc transport
> >
> > On 3/5/20 8:06 AM, Sudeep Holla wrote:
> > > On Thu, Mar 05, 2020 at 11:25:35AM +0000, Peng Fan wrote:
> > >
> > > [...]
> > >
> > >>>
> > >>> Yes, this may fix the issue. However I would like to know if we need
> > >>> to support multiple channels/shared memory simultaneously. It is
> > >>> fair requirement and may need some work which should be fine.
> > >>
> > >> Do you have any suggestions? Currently I have not worked out an good
> > >> solution.
> > >>
> > >
> > > TBH, I haven't given it a much thought. I would like to know if people
> > > are happy with just one SMC channel for SCMI or do they need more ?
> > > If they need it, we can try to solve it. Otherwise, what you have will
> > > suffice IMO.
> >
> > On our platforms we have one channel/shared memory area/mailbox
> > instance for all standard SCMI protocols, and we have a separate
> > channel/shared memory area/mailbox driver instance for a proprietary one.
> > They happen to have difference throughput requirements, hence the split.
> >

OK, when you refer proprietary protocol, do you mean outside the scope of
SCMI ? The reason I ask is SCMI allows vendor specific protocols and if
you are using other channel for that, it still make sense to add
multi-channel support here.

> > If I read Peng's submission correctly, it seems to me that the usage model
> > described before is still fine.
>
> Thanks.
>
> Sudeep,
>
> Then should I repost with the global mutex added?
>

Sure, you can send the updated. I will think about adding support for more
than one channel and send a patch on top of it if I get around it.

Note that I sent PR for v5.7 last earlier this week, so this will be for v5.8

--
Regards,
Sudeep