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

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Message-ID: <0552e10d-acde-33cd-7f9c-5d7b28fee735@huawei.com>
Date: Tue, 11 Mar 2025 19:32:34 +0800
From: "lihuisong (C)" <lihuisong@...wei.com>
To: Sudeep Holla <sudeep.holla@....com>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: Jassi Brar <jassisinghbrar@...il.com>, Adam Young
	<admiyo@...amperecomputing.com>, Robbie King <robbiek@...ghtlabs.com>
Subject: Re: [PATCH v2 07/13] mailbox: pcc: Always map the shared memory
 communication address


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?
Do we need to make a statement that the two iommaps have no impact on 
the existing mbox client drivers?
>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
Acked-by: Huisong Li <lihuisong@...wei.com>
Tested-by: Huisong Li <lihuisong@...wei.com>
>