From: Alex Elder <elder@linaro.org>
To: Johannes Berg <johannes@sipsolutions.net>,
davem@davemloft.net, arnd@arndb.de, bjorn.andersson@linaro.org,
ilias.apalodimas@linaro.org, Dan Williams <dcbw@redhat.com>
Cc: devicetree@vger.kernel.org, syadagir@codeaurora.org,
ejcaruso@google.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, evgreen@chromium.org,
linux-arm-kernel@lists.infradead.org,
linux-arm-msm@vger.kernel.org, subashab@codeaurora.org,
linux-soc@vger.kernel.org, abhishek.esse@gmail.com,
cpratapa@codeaurora.org, benchan@google.com
Subject: Re: WWAN Controller Framework (was IPA [PATCH v2 00/17])
Date: Wed, 26 Jun 2019 08:40:11 -0500 [thread overview]
Message-ID: <25bb0936-686c-101b-c5a4-474ed37536aa@linaro.org> (raw)
In-Reply-To: <f1243295f088b70d48e4b832a28f79c0cd84ca1c.camel@sipsolutions.net>
On 6/25/19 9:34 AM, Johannes Berg wrote:
> On Mon, 2019-06-24 at 12:06 -0500, Alex Elder wrote:
>
>>> OK I want to try to organize a little more concisely some of the
>>> discussion on this, because there is a very large amount of volume
>>> to date and I think we need to try to narrow the focus back down
>>> again.
>
> Sounds good to me!
. . .
>>> - A WWAN unit shall implement a *WWAN control function*, used to
>>> manage the use of other WWAN functions, as well as the WWAN unit
>>> itself.
>
> I think here we need to be more careful. I don't know how you want to
> call it, but we actually have multiple levels of control here.
I completely agree with you. From what I understand there exists
a control channel (or even more than one?) that serves a very
specific purpose in modem management. The main reason I mention
the WWAN control function is that someone (maybe you) indicated
that a control channel automatically gets created.
But I agree, we need to be careful to avoid confusion here.
> You have
> * hardware control, to control how you actually use the (multiple or
> not) physical communication channel(s) to the WWAN unit
> * this is partially exposed to userspace via the WWAN netlink family or
> something like that, so userspace can create new netdevs to tx/rx
> with the "data function" and to the network; note that it could be
> one or multiple
> * WWAN control, which is typically userspace communicating with the
> WWAN control function in the WWAN unit, but this can take different
> forms (as I mentioned earlier, e.g. AT commands, MBIM, QMI)
>
>>> - The AP communicates with a WWAN function using a WWAN protocol.
>
> Right, that's just device specific (IPA vs. Intel vs. ...)
>
>>> - A WWAN physical channel can be *multiplexed*, in which case it
>>> carries the data for one or more *WWAN logical channels*.
>
> This ... depends a bit on how you exactly define a physical channel
> here. Is that, to you, the PCIe/USB link? In that case, yes, obviously
> you have only one physical channel for each WWAN unit.
I think that was what I was trying to capture. There exists
one or more "physical" communication paths between the AP
and WWAN unit/modem. And while one path *could* carry just
one type of traffic, it could also carry multiple logical
channels of traffic by multiplexing.
> However, I'd probably see this slightly differently, because e.g. the
> Intel modem has multiple DMA engines, and so you actually have multiple
> DMA rings to talk to the WWAN unit, and I'd have called each DMA ring a
> physical channel. And then, you just have a 1:1 from physical to logical
> channel since it doesn't actually carry a multiplexing protocol.
Understood.
. . .
> I only disagree slightly on the control planes (there are multiple, and
> multiple options for the "Control function" one), and on the whole
> notion of physical link/logical link/multiplexing which is device
> specific.
>
>>> And if I understand it right, the purpose of the generic framework
>>> being discussed is to define a common mechanism for managing (i.e.,
>>> discovering, creating, destroying, querying, configuring, enabling,
>>> disabling, etc.) WWAN units and the functions they implement, along
>>> with the communication and logical channels used to communicate with
>>> them.
>
> Well, some subset of that matrix, the framework won't actually destroy
> WWAN units I hope ;-)
Hardware self-destruct would be an optional behavior.
> But yes. I'd probably captured it in layers, and say that we have a
>
> WWAN framework layer
> - discover, query, configure WWAN units
> - enable, disable channels to the functions inside the WWAN units
>
> WWAN device driver
> - implement (partial) API offered by WWAN framework layer to allow
> these things
> (sometimes may not allow creating more control or data channels for
> example, and fixed function channels are precreated, but then can
> still discover data about the device and configure the channels
> - implement the device-specific protocols etc. necessary to achieve
> this
>
> Userspace
> - uses control function channel (e.g. TTY) to talk directly to the WWAN
> unit's control function
> - uses WWAN framework APIs to create/configure/... (other) function
> channels
> (it may be necessary to create a control channel even, before being
> able to use it, since different options (AT/MBIM/QMI) may be there
> - configures netdevs (data function channels) after their creation
I don't think I have any argument with this. I'm going to try to
put together something that goes beyond what I wrote in this message,
to try to capture what I think we agree on in a sort of loose design
document.
Thanks Johannes.
-Alex
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next prev parent reply other threads:[~2019-06-26 13:40 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-31 3:53 [PATCH v2 00/17] net: introduce Qualcomm IPA driver Alex Elder
2019-05-31 3:53 ` [PATCH v2 01/17] bitfield.h: add FIELD_MAX() and field_max() Alex Elder
2019-05-31 3:53 ` [PATCH v2 02/17] dt-bindings: soc: qcom: add IPA bindings Alex Elder
2019-06-10 22:08 ` Rob Herring
2019-06-11 2:11 ` Alex Elder
2019-07-03 15:09 ` Alex Elder
2019-05-31 3:53 ` [PATCH v2 03/17] soc: qcom: ipa: main code Alex Elder
2019-05-31 21:50 ` David Miller
2019-05-31 22:25 ` Alex Elder
2019-05-31 3:53 ` [PATCH v2 04/17] soc: qcom: ipa: configuration data Alex Elder
2019-05-31 3:53 ` [PATCH v2 05/17] soc: qcom: ipa: clocking, interrupts, and memory Alex Elder
2019-05-31 3:53 ` [PATCH v2 06/17] soc: qcom: ipa: GSI headers Alex Elder
2019-05-31 3:53 ` [PATCH v2 07/17] soc: qcom: ipa: the generic software interface Alex Elder
2019-05-31 3:53 ` [PATCH v2 08/17] soc: qcom: ipa: GSI transactions Alex Elder
2019-05-31 3:53 ` [PATCH v2 09/17] soc: qcom: ipa: IPA interface to GSI Alex Elder
2019-05-31 3:53 ` [PATCH v2 10/17] soc: qcom: ipa: IPA endpoints Alex Elder
2019-05-31 3:53 ` [PATCH v2 11/17] soc: qcom: ipa: immediate commands Alex Elder
2019-05-31 3:53 ` [PATCH v2 12/17] soc: qcom: ipa: IPA network device and microcontroller Alex Elder
2019-05-31 3:53 ` [PATCH v2 13/17] soc: qcom: ipa: AP/modem communications Alex Elder
2019-05-31 3:53 ` [PATCH v2 14/17] soc: qcom: ipa: support build of IPA code Alex Elder
2019-05-31 3:53 ` [PATCH v2 15/17] MAINTAINERS: add entry for the Qualcomm IPA driver Alex Elder
2019-05-31 3:53 ` [PATCH v2 16/17] arm64: dts: sdm845: add IPA information Alex Elder
2019-05-31 3:53 ` [PATCH v2 17/17] arm64: defconfig: enable build of IPA code Alex Elder
2019-05-31 14:58 ` [PATCH v2 00/17] net: introduce Qualcomm IPA driver Dan Williams
2019-05-31 16:36 ` Alex Elder
2019-05-31 19:19 ` Arnd Bergmann
2019-05-31 20:47 ` Alex Elder
2019-05-31 21:12 ` Arnd Bergmann
2019-05-31 22:08 ` Alex Elder
2019-06-07 17:43 ` Alex Elder
2019-05-31 23:33 ` Bjorn Andersson
2019-05-31 23:59 ` Subash Abhinov Kasiviswanathan
2019-06-03 10:04 ` Arnd Bergmann
2019-06-03 13:32 ` Alex Elder
2019-06-04 8:13 ` Arnd Bergmann
2019-06-04 15:18 ` Dan Williams
2019-06-04 20:04 ` Arnd Bergmann
2019-06-04 21:29 ` Dan Williams
2019-06-06 17:42 ` Alex Elder
2019-06-11 8:12 ` Johannes Berg
2019-06-11 11:56 ` Arnd Bergmann
2019-06-11 15:53 ` Dan Williams
2019-06-11 16:52 ` Subash Abhinov Kasiviswanathan
2019-06-11 17:22 ` Dan Williams
2019-06-12 8:31 ` Arnd Bergmann
2019-06-12 14:27 ` Dan Williams
2019-06-12 15:06 ` Arnd Bergmann
2019-06-17 11:42 ` Johannes Berg
2019-06-17 12:25 ` Johannes Berg
2019-06-18 15:20 ` Alex Elder
2019-06-18 18:06 ` Dan Williams
2019-06-24 16:21 ` Alex Elder
2019-06-25 14:14 ` Johannes Berg
2019-06-26 13:36 ` Alex Elder
2019-06-26 17:55 ` Johannes Berg
2019-06-18 18:48 ` Johannes Berg
2019-06-24 16:21 ` Alex Elder
2019-06-18 13:45 ` Alex Elder
2019-06-18 19:03 ` Johannes Berg
2019-06-18 20:09 ` Arnd Bergmann
2019-06-18 20:15 ` Johannes Berg
2019-06-18 20:33 ` Arnd Bergmann
2019-06-18 20:39 ` Johannes Berg
2019-06-18 21:06 ` Arnd Bergmann
2019-06-19 20:56 ` Dan Williams
2019-06-24 16:21 ` Alex Elder
2019-06-24 16:40 ` Arnd Bergmann
2019-06-25 14:19 ` Johannes Berg
2019-06-26 13:39 ` Alex Elder
2019-06-26 13:58 ` Arnd Bergmann
2019-06-26 17:48 ` Johannes Berg
2019-06-26 17:45 ` Johannes Berg
2019-06-26 13:51 ` Alex Elder
2019-06-17 11:28 ` Johannes Berg
2019-06-18 13:16 ` Alex Elder
2019-06-18 13:48 ` Arnd Bergmann
2019-06-18 19:14 ` Johannes Berg
2019-06-18 19:59 ` Arnd Bergmann
2019-06-18 20:36 ` Johannes Berg
2019-06-18 20:55 ` Arnd Bergmann
2019-06-18 21:02 ` Johannes Berg
2019-06-18 21:15 ` Subash Abhinov Kasiviswanathan
2019-06-19 12:23 ` Arnd Bergmann
2019-06-19 18:47 ` Subash Abhinov Kasiviswanathan
2019-06-20 1:25 ` Dan Williams
2019-06-24 16:21 ` Alex Elder
2019-06-17 12:14 ` Johannes Berg
2019-06-18 14:00 ` Alex Elder
2019-06-18 19:22 ` Johannes Berg
2019-06-24 16:21 ` Alex Elder
2019-06-03 14:50 ` Dan Williams
2019-06-03 14:54 ` Dan Williams
2019-06-03 15:52 ` Alex Elder
2019-06-03 16:18 ` Dan Williams
2019-06-03 19:04 ` Subash Abhinov Kasiviswanathan
2019-06-04 15:21 ` Dan Williams
2019-05-31 23:27 ` Bjorn Andersson
2019-06-10 2:44 ` Alex Elder
2019-06-20 13:41 ` [PATCH v2 05/17] soc: qcom: ipa: clocking, interrupts, and memory Hillf Danton
2019-06-24 16:30 ` WWAN Controller Framework (was IPA [PATCH v2 00/17]) Alex Elder
2019-06-24 17:06 ` Alex Elder
2019-06-25 14:34 ` Johannes Berg
2019-06-26 13:40 ` Alex Elder [this message]
2019-06-26 17:58 ` Johannes Berg
2019-06-24 19:54 ` Dan Williams
2019-06-24 21:16 ` Alex Elder
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