linux-kernel - Re: [PATCH net-next v22 1/2] mailbox/pcc: support mailbox management of the shared buffer

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Message-ID: <6f29a47b-13a3-4e41-808b-e29a41799ec1@amperemail.onmicrosoft.com>
Date: Mon, 14 Jul 2025 19:02:04 -0400
From: Adam Young <admiyo@...eremail.onmicrosoft.com>
To: admiyo@...amperecomputing.com, Sudeep Holla <sudeep.holla@....com>,
 Jassi Brar <jassisinghbrar@...il.com>, Robert Moore
 <robert.moore@...el.com>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
 Len Brown <lenb@...nel.org>
Cc: 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 net-next v22 1/2] mailbox/pcc: support mailbox management
 of the shared buffer

Internal review discovered an error

On 7/10/25 15:12, admiyo@...amperecomputing.com wrote:
> +	if (pchan->chan.rx_alloc)
> +		ret = pcc_write_to_buffer(chan, data);

This is the wrong check. The rx_alloc is expected to be used  for the 
type4, and the will be called from the type 3.

Going to add an explicit flag instead.

> +	pcc_hdr = pchan->chan.shmem;
> +	if (ioread32(&pcc_hdr->flags) & PCC_CMD_COMPLETION_NOTIFY)
> +		pchan->chan.irq_ack = true;

This flag can be removed and replaced  with a check of the value in the 
original buffer, which is held in chan->current_req.

Updated version of the patch series to follow.