> Subject: Re: [PATCH 1/4] firmware: arm_scmi: Make mutex channel specific
>
> On Wed, Apr 01, 2020 at 01:12:37AM +0000, Peng Fan wrote:
> > Hi Sudeep,
> >
> > > Subject: [PATCH 1/4] firmware: arm_scmi: Make mutex channel specific
> > >
> > > In order to support multiple SMC/HVC transport channels with
> > > associated shared memory,
> >
> > Does this mean each channel will have its own shared memory? Or All
> > channels share the same shared memory?
> >
>
> It depends on platform firmware and DT. If there is only one shmem at the top
> level scmi node, all share that single channel. If some/all protocols have their
> own channel, they there must be shmem entry in the corresponding child
> node.
>
> > it is better to maintain the mutex per channel instead of
> > > existing global one.
> >
> > If all channels shared the same memory, use per channel mutex lock
> > will not be able to prevent other channels accessing shared memory at
> > the same time.
> >
>
> No we don't create channel per protocol. If they share, we just share the
> channel pointer. Look at:
>
> if (!info->desc->ops->chan_available(dev, idx)) {
> cinfo = idr_find(idr, SCMI_PROTOCOL_BASE);
> if (unlikely(!cinfo)) /* Possible only if platform has no Rx */
> return -EINVAL;
> goto idr_alloc;
> }
>
> If a protocol doesn't have a dedicated channel, we just assign the base
> protocol channel to it. We don't call chan_setup at all on that channel.
> Your patch assumed so but the core driver never did that.
>
> Hope this clarifies you doubt.
Yes. Thanks for the explainaiton.
Thanks,
Peng.
>
> --
> Regards,
> Sudeep
