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[71.195.29.92]) by smtp.googlemail.com with ESMTPSA id v13sm14220933ioq.13.2019.06.24.09.21.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Jun 2019 09:21:29 -0700 (PDT) Subject: Re: [PATCH v2 00/17] net: introduce Qualcomm IPA driver To: Johannes Berg , Arnd Bergmann , Dan Williams Cc: Subash Abhinov Kasiviswanathan , abhishek.esse@gmail.com, Ben Chan , Bjorn Andersson , cpratapa@codeaurora.org, David Miller , DTML , Eric Caruso , evgreen@chromium.org, Ilias Apalodimas , Linux ARM , linux-arm-msm@vger.kernel.org, Linux Kernel Mailing List , linux-soc@vger.kernel.org, Networking , syadagir@codeaurora.org References: <380a6185-7ad1-6be0-060b-e6e5d4126917@linaro.org> <36bca57c999f611353fd9741c55bb2a7@codeaurora.org> <153fafb91267147cf22e2bf102dd822933ec823a.camel@redhat.com> <850eed1d-0fec-c396-6e91-b5f1f8440ded@linaro.org> <967604dd8d466a99b865649174f8b9cd34b2560e.camel@sipsolutions.net> From: Alex Elder Message-ID: Date: Mon, 24 Jun 2019 11:21:28 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <967604dd8d466a99b865649174f8b9cd34b2560e.camel@sipsolutions.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/18/19 1:48 PM, Johannes Berg wrote: > Just to add to Dan's response, I think he's captured our discussions and > thoughts well. > >> First, a few terms (correct or improve as you like): > > Thanks for defining, we don't do that nearly often enough. > >> - WWAN device is a hardware device (like IPA) that presents a >> connection between AP and modem, and presents an interface >> that allows the use of that connection to be managed. > > Yes. But I was actually thinking of a "wwan_dev" to be a separate > structure, not *directly* owned by a single driver and used to represent > the hardware like a (hypothetical) "struct ipa_dev". I think you're talking about creating a coordination interface that allows multiple drivers to interact with a WWAN device, which might implement several independent features. >> - WWAN netdevice represents a Linux network interface, with its >> operations and queues, etc., but implements a standardized >> set of WWAN-specific operations. It represents a logical >> ' channel whose data is multiplexed over the WWAN device. > > I'm not sure I'd asy it has much WWAN-specific operations? But yeah, I > guess it might. I want to withdraw this notion of a "WWAN netdevice"... >> - WWAN channel is a user space abstraction that corresponds >> with a WWAN netdevice (but I'm not clear on all the ways >> they differ or interact). > > As Dan said, this could be a different abstraction than a netdevice, > like a TTY, etc. Right, I get that now. . . . >> - Which WWAN channel attributes must be set *before* the >> channel is activated, and can't be changed? Are there any >> that can be changed dynamically? > > It's a good question. I threw a "u32 pdn" in there, but I'm not actually > sure that's what you *really* need? > > Maybe the modem and userspace just agree on some arbitrary "session > identifier"? Dan mentions "MUX ID" or "MBIM Session ID", maybe there > really is no good general term for this and we should just call it a > "session identifier" and agree that it depends on the control protocol > (MBIM vs. QMI vs. ...)? > >> And while the whole point of this is to make things generic, >> it might be nice to have a way to implement a new feature >> before it can be "standardized". > > Not sure I understand this? I'm talking about a way to experiment with new functionality in a way that's explicitly not part of the interface. But doing that isn't necessary and it's probably not a good idea anyway. > FWIW, I actually came to this because we want to upstream a driver for > an Intel modem, but ... can't really make up our mind on whether or not > to use VLAN tags, something like rmnet (but we obviously cannot use > rmnet, so that'd be another vendor specific interface like rmnet), or > sysfs, or any of the other methods we have today ... :-) OK cool then we have some common needs. Let's get this defined so we can use it for both! -Alex > > johannes >