netdev - Re: [PATCH v6 1/2] mctp pcc: Check before sending MCTP PCC response ACK

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Message-ID: <f44f9b12-5cb1-af1d-5e2f-9a06ad648347@huawei.com>
Date: Fri, 1 Nov 2024 09:30:10 +0800
From: "lihuisong (C)" <lihuisong@...wei.com>
To: Adam Young <admiyo@...eremail.onmicrosoft.com>,
	<admiyo@...amperecomputing.com>
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>, "Len
 Brown" <lenb@...nel.org>, "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Robert Moore <robert.moore@...el.com>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>, Jonathan Cameron
	<Jonathan.Cameron@...wei.com>, Jassi Brar <jassisinghbrar@...il.com>, "Sudeep
 Holla" <sudeep.holla@....com>
Subject: Re: [PATCH v6 1/2] mctp pcc: Check before sending MCTP PCC response
 ACK

Hi Adam,

All modifications in the patch is done for pcc instead of mctp.
Suggest that use the prefix "mailbox: pcc: xxxx".
Please find my following reply.


在 2024/11/1 8:16, Adam Young 写道:
>
> On 10/30/24 05:45, lihuisong (C) wrote:
>>> + check_and_ack(pchan, chan);
>>>       pchan->chan_in_use = false;
>>>         return IRQ_HANDLED;
>>> @@ -352,6 +368,9 @@ pcc_mbox_request_channel(struct mbox_client *cl, 
>>> int subspace_id)
>>>       if (rc)
>>>           return ERR_PTR(rc);
>>>   +    pchan->shmem_base_addr = devm_ioremap(chan->mbox->dev,
>>> +                          pchan->chan.shmem_base_addr,
>>> +                          pchan->chan.shmem_size);
>> Currently, the PCC mbox client does ioremap after requesting PCC 
>> channel.
>> Thus all current clients will ioremap twice. This is not good to me.
>> How about add a new interface and give the type4 client the right to 
>> decide whether to reply in rx_callback?
>
>
> I do agree that is a cleaner implementation, but I don't have a way of 
> testing the other drivers, and did not want to break them. I think 
> your driver is the only that makes use of it, so we can certainly come 
> up with a common approach.
I understand what you are concerned about.
But this duplicate ioremap also works for all PCC clients no matter 
which type they used. It has very wide influence.
My driver just uses type3 instead of type4. What's more, AFAICS, it 
doesn't seem there is type4 client driver in linux.
Therefore, determining whether type4 client driver needs to reply to 
platform has the minimum or even no impact in their rx_callback.
>
> The mailbox interface does not allow a return code from 
> mbox_chan_received_data, which is what I originally wanted.  If that 
> could return multiple status codes, one of them could indicate the 
> need  to send the interrupt back.  Otherwise, we need to query the 
> driver to read the shared memory again.
yes
>
> .