netdev - Re: [PATCH v23 1/2] mailbox/pcc: support mailbox management of the shared buffer

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Message-ID: <20250715140859.GB721198@horms.kernel.org>
Date: Tue, 15 Jul 2025 15:08:59 +0100
From: Simon Horman <horms@...nel.org>
To: admiyo@...amperecomputing.com
Cc: Sudeep Holla <sudeep.holla@....com>,
	Jassi Brar <jassisinghbrar@...il.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>, Robert Moore <robert.moore@...el.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jeremy Kerr <jk@...econstruct.com.au>,
	Matt Johnston <matt@...econstruct.com.au>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Huisong Li <lihuisong@...wei.com>
Subject: Re: [PATCH v23 1/2] mailbox/pcc: support mailbox management of the
 shared buffer

On Mon, Jul 14, 2025 at 08:10:07PM -0400, admiyo@...amperecomputing.com wrote:
> From: Adam Young <admiyo@...amperecomputing.com>
> 
> Define a new, optional, callback that allows the driver to
> specify how the return data buffer is allocated.  If that callback
> is set,  mailbox/pcc.c is now responsible for reading from and
> writing to the PCC shared buffer.
> 
> This also allows for proper checks of the Commnand complete flag
> between the PCC sender and receiver.

Command

> 
> For Type 4 channels, initialize the command complete flag prior
> to accepting messages.
> 
> Since the mailbox does not know what memory allocation scheme
> to use for response messages, the client now has an optional
> callback that allows it to allocate the buffer for a response
> message.
> 
> When an outbound message is written to the buffer, the mailbox
> checks for the flag indicating the client wants an tx complete
> notification via IRQ.  Upon receipt of the interrupt It will
> pair it with the outgoing message. The expected use is to
> free the kernel memory buffer for the previous outgoing message.
> 
> Signed-off-by: Adam Young <admiyo@...amperecomputing.com>

...