netdev - Re: [PATCH v10 09/26] cxl: support device identification without mailbox

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Message-ID: <9ce2dc57-ad51-4587-8099-60f568984b84@amd.com>
Date: Thu, 6 Feb 2025 18:10:14 +0000
From: Alejandro Lucero Palau <alucerop@....com>
To: Ira Weiny <ira.weiny@...el.com>, linux-cxl@...r.kernel.org,
 netdev@...r.kernel.org, dan.j.williams@...el.com, edward.cree@....com,
 davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
 edumazet@...gle.com, dave.jiang@...el.com
Subject: Re: [PATCH v10 09/26] cxl: support device identification without
 mailbox

On 2/5/25 21:45, Ira Weiny wrote:
> alucerop@ wrote:
>> From: Alejandro Lucero <alucerop@....com>
>>
>> Type3 relies on mailbox CXL_MBOX_OP_IDENTIFY command for initializing
>> memdev state params.
>>
>> Allow a Type2 driver to initialize same params using an info struct and
>> assume partition alignment not required by now.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@....com>
> This is exactly the type of thing I was hoping to avoid by removing these
> members from the mds.  There is no reason you should have to fake these
> values within an mds just to create partitions in the device state.

Let's be practical here.

A type2 without a mailbox needs to give that information for building up 
the DPA partitions. Before it was about dealing with DPA resources from 
the accel driver, but I do not think an accel driver should handle any 
partition setup at all. Mainly because there is code now doing that in 
the cxl core which can be used for accel drivers without requiring too 
much effort. You can see what the sfc driver does now, and it is 
equivalent to the current pci driver. An accel driver with a device 
supporting a mailbox will do exactly the same than the pci driver.

For avoiding the mds fields the weight should not be on the accel 
driver. This patch adds a way for giving the required (and little) info 
to the core for building the partitions. So if you or Dan suggest this 
is wrong and the accel driver should deal with the intrinsics of DPA 
partitions, I will fight against it :-)

I'm quite happy with the DPA partition work, with the result of current 
v10 being simpler and cleaner. But it is time to get the patchsets 
depending on that cleaning work going forward.