Re: [PATCH v2 07/13] mailbox: pcc: Always map the shared memory communication address

[lihuisong (C)]

在 2025/3/11 19:56, Sudeep Holla 写道:
> On Tue, Mar 11, 2025 at 07:32:34PM +0800, lihuisong (C) wrote:
> > 在 2025/3/6 0:38, Sudeep Holla 写道:
> > > Currently the shared memory communication address was mapped by the
> > > mailbox client drivers leading to all sorts of inconsistencies.
> > >
> > > It also has resulted in the inconsistent attributes used while mapping
> > > the shared memory regions.
> > >
> > > In order to remove/eliminate any issues, let us ensures the shared
> > > memory address is always mapped and unmapped when the PCC channels are
> > > requested and release.
> > >
> > > We need to map them as the ACPI PCCT associates these shared memory
> > > with each channel subspace and may need use the status or the flags in
> > > the headers of those shared memory communication address regions to
> > > manage the transport/channel.
> > >
> > > Since there are no users of pcc_chan_ioremap() and also it is mapped
> > > by default, we can stop exporting it and merge the functionality into
> > > pcc_mbox_request_channel().
> > There are two ioremap for the existing mbox client driver after this patch.
> > The existing mbox client driver would not use this variable, and no one else
> > uses it. So it is safe, right?
> IIUC yes, it should be fine.
>
> > Do we need to make a statement that the two iommaps have no impact on the
> > existing mbox client drivers?
> We can add one, but again it will be become obsolete once we change driver
> to use this new mapping. That's why I didn't add it. We can merge all the
> changes together if that is the concern. I am fine either way.
I also tested the case with this patch and no modification of driver.
I didn't find any other issue.
IMO, we should make a statement for this anyway.

/Huisong
>