linux-kernel - Re: [PATCH 1/6] Revert "mailbox/pcc: support mailbox management of the shared buffer"

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Message-ID: <6b3ca901-025d-44b8-9558-6ad5a491807e@huawei.com>
Date: Mon, 20 Oct 2025 11:46:37 +0800
From: "lihuisong (C)" <lihuisong@...wei.com>
To: Sudeep Holla <sudeep.holla@....com>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: Adam Young <admiyo@...amperecomputing.com>, Robbie King
	<robbiek@...ghtlabs.com>, Jassi Brar <jassisinghbrar@...il.com>, "Cristian
 Marussi" <cristian.marussi@....com>
Subject: Re: [PATCH 1/6] Revert "mailbox/pcc: support mailbox management of
 the shared buffer"


在 2025/10/17 3:08, Sudeep Holla 写道:
> This reverts commit 5378bdf6a611a32500fccf13d14156f219bb0c85.
>
> Commit 5378bdf6a611 ("mailbox/pcc: support mailbox management of the shared buffer")
> attempted to introduce generic helpers for managing the PCC shared memory,
> but it largely duplicates functionality already provided by the mailbox
> core and leaves gaps:
>
> 1. TX preparation: The mailbox framework already supports this via
>    ->tx_prepare callback for mailbox clients. The patch adds
>    pcc_write_to_buffer() and expects clients to toggle pchan->chan.manage_writes,
>    but no drivers set manage_writes, so pcc_write_to_buffer() has no users.
>
> 2. RX handling: Data reception is already delivered through
>     mbox_chan_received_data() and client ->rx_callback. The patch adds an
>     optional pchan->chan.rx_alloc, which again has no users and duplicates
>     the existing path.
>
> 3. Completion handling: While adding last_tx_done is directionally useful,
>     the implementation only covers Type 3/4 and fails to handle the absence
>     of a command_complete register, so it is incomplete for other types.
>
> Given the duplication and incomplete coverage, revert this change. Any new
> requirements should be addressed in focused follow-ups rather than bundling
> multiple behavioral changes together.
>
> Fixes: 5378bdf6a611 ("mailbox/pcc: support mailbox management of the shared buffer")
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Yeah, there are some duplications. I remember I also mentioned before.
Acked-by: lihuisong@...wei.com