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Date:   Thu, 8 Jun 2023 18:07:20 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     davem@davemloft.net, edumazet@google.com, pabeni@redhat.com,
        mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        loic.poulain@linaro.org
Subject: Re: [PATCH v2 0/2] Add MHI Endpoint network driver
Message-ID: <20230608123720.GC5672@thinkpad>
References: <20230607152427.108607-1-manivannan.sadhasivam@linaro.org>
 <20230607094922.43106896@kernel.org>
 <20230607171153.GA109456@thinkpad>
 <20230607104350.03a51711@kernel.org>
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On Wed, Jun 07, 2023 at 10:43:50AM -0700, Jakub Kicinski wrote:
> On Wed, 7 Jun 2023 22:41:53 +0530 Manivannan Sadhasivam wrote:
> > > In any case, I'm opposed to reuse of the networking stack to talk
> > > to firmware. It's a local device. The networking subsystem doesn't
> > > have to cater to fake networks. Please carry:
> > > 
> > > Nacked-by: Jakub Kicinski <kuba@kernel.org>
> > > 
> > > if there are future submissions.  
> > 
> > Why shouldn't it be? With this kind of setup one could share the data connectivity
> > available in the device with the host over IP tunneling. If the IP source in the
> > device (like modem DSP) has no way to be shared with the host, then those IP
> > packets could be tunneled through this interface for providing connectivity to
> > the host.
> > 
> > I believe this is a common usecase among the PCIe based wireless endpoint
> > devices.
> 
> We can handwave our way into many scenarios and terrible architectures.
> I don't see any compelling reason to merge this.

These kind of usecases exist in the products out there in the market. Regarding
your comment on "opposed to reuse of the network stack to talk to firmware", it
not the just the firmware, it is the device in general that is talking to the
host over this interface. And I don't see how different it is from the host
perspective.

And these kind of scenarios exist with all types of interfaces like usb-gadget,
virtio etc... So not sure why the rule is different for networking subsystem.

- Mani

-- 
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