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Subject: Re: [PATCH v2 00/17] net: introduce Qualcomm IPA driver
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        Dan Williams <dcbw@redhat.com>,
        Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>,
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        cpratapa@codeaurora.org, David Miller <davem@davemloft.net>,
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        Eric Caruso <ejcaruso@google.com>, evgreen@chromium.org,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-arm-msm@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-soc@vger.kernel.org, Networking <netdev@vger.kernel.org>,
        syadagir@codeaurora.org
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From:   Alex Elder <elder@linaro.org>
Message-ID: <2d40bbcc-1d29-3aa7-e8cb-b0bc5835b8dc@linaro.org>
Date:   Wed, 26 Jun 2019 08:51:02 -0500
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On 6/24/19 11:40 AM, Arnd Bergmann wrote:
> On Mon, Jun 24, 2019 at 6:21 PM Alex Elder <elder@linaro.org> wrote:
>> On 6/18/19 2:03 PM, Johannes Berg wrote:
>>
>>> Really there are two possible ways (and they intersect to some extent).

. . .

>>> The other is something like IPA or the Intel modem driver, where the
>>> device is actually a single (e.g. PCIe) device and just has a single
>>> driver, but that single driver offers different channels.
>>
>> What I don't like about this is that it's more monolithic.  It
>> seems better to have the low-level IPA or Intel modem driver (or
>> any other driver that can support communication between the AP
>> and WWAN device) present communication paths that other function-
>> specific drivers can attach to and use.
> 
> I did not understand Johannes description as two competing models
> for the same code, but rather two kinds of existing hardware that
> a new driver system would have to deal with.

Based on my understanding of what he said in a message I just
responded to, I think you are exactly right.

. . .

> What we should try to avoid though is a way to add driver private
> interfaces that risk having multiple drivers create similar functionality
> in incompatible ways.

Agreed.

					-Alex