From: Dan Williams <dcbw@redhat.com>
To: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: DTML <devicetree@vger.kernel.org>,
syadagir@codeaurora.org, Eric Caruso <ejcaruso@google.com>,
Arnd Bergmann <arnd@arndb.de>,
Networking <netdev@vger.kernel.org>,
linux-arm-msm@vger.kernel.org,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
evgreen@chromium.org, abhishek.esse@gmail.com,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Alex Elder <elder@linaro.org>,
linux-soc@vger.kernel.org, David Miller <davem@davemloft.net>,
cpratapa@codeaurora.org, Ben Chan <benchan@google.com>
Subject: Re: [PATCH v2 00/17] net: introduce Qualcomm IPA driver
Date: Mon, 03 Jun 2019 09:50:24 -0500 [thread overview]
Message-ID: <99b9a24b229975689fb4686915190200606e8afc.camel@redhat.com> (raw)
In-Reply-To: <d76a710d45dd7df3a28afb12fc62cf14@codeaurora.org>
On Fri, 2019-05-31 at 17:59 -0600, Subash Abhinov Kasiviswanathan
wrote:
> On 2019-05-31 17:33, Bjorn Andersson wrote:
> > On Fri 31 May 13:47 PDT 2019, Alex Elder wrote:
> >
> > > On 5/31/19 2:19 PM, Arnd Bergmann wrote:
> > > > On Fri, May 31, 2019 at 6:36 PM Alex Elder <elder@linaro.org>
> > > > wrote:
> > > > > On 5/31/19 9:58 AM, Dan Williams wrote:
> > > > > > On Thu, 2019-05-30 at 22:53 -0500, Alex Elder wrote:
> > > > > >
> > > > > > My question from the Nov 2018 IPA rmnet driver still
> > > > > > stands; how does
> > > > > > this relate to net/ethernet/qualcomm/rmnet/ if at all? And
> > > > > > if this is
> > > > > > really just a netdev talking to the IPA itself and
> > > > > > unrelated to
> > > > > > net/ethernet/qualcomm/rmnet, let's call it "ipa%d" and stop
> > > > > > cargo-
> > > > > > culting rmnet around just because it happens to be a net
> > > > > > driver for a
> > > > > > QC SoC.
> > > > >
> > > > > First, the relationship between the IPA driver and the rmnet
> > > > > driver
> > > > > is that the IPA driver is assumed to sit between the rmnet
> > > > > driver
> > > > > and the hardware.
> > > >
> > > > Does this mean that IPA can only be used to back rmnet, and
> > > > rmnet
> > > > can only be used on top of IPA, or can or both of them be
> > > > combined
> > > > with another driver to talk to instead?
> > >
> > > No it does not mean that.
> > >
> > > As I understand it, one reason for the rmnet layer was to
> > > abstract
> > > the back end, which would allow using a modem, or using something
> > > else (a LAN?), without exposing certain details of the hardware.
> > > (Perhaps to support multiplexing, etc. without duplicating that
> > > logic in two "back-end" drivers?)
> > >
> > > To be perfectly honest, at first I thought having IPA use rmnet
> > > was a cargo cult thing like Dan suggested, because I didn't see
> > > the benefit. I now see why one would use that pass-through layer
> > > to handle the QMAP features.
> > >
> > > But back to your question. The other thing is that I see no
> > > reason the IPA couldn't present a "normal" (non QMAP) interface
> > > for a modem. It's something I'd really like to be able to do,
> > > but I can't do it without having the modem firmware change its
> > > configuration for these endpoints. My access to the people who
> > > implement the modem firmware has been very limited (something
> > > I hope to improve), and unless and until I can get corresponding
> > > changes on the modem side to implement connections that don't
> > > use QMAP, I can't implement such a thing.
> > >
> >
> > But any such changes would either be years into the future or for
> > specific devices and as such not applicable to any/most of devices
> > on
> > the market now or in the coming years.
> >
> >
> > But as Arnd points out, if the software split between IPA and rmnet
> > is
> > suboptimal your are encouraged to fix that.
> >
> > Regards,
> > Bjorn
>
> The split rmnet design was chosen because we could place rmnet
> over any transport - IPA, PCIe (https://lkml.org/lkml/2018/4/26/1159)
> or USB.
Yeah, that's what I was looking for clarification on :) Clearly since
rmnet can have many transports it should be able to be used by
different HW drivers, be that qmi_wwan, IPA, and maybe even
rmnet_smd.c?
> rmnet registers a rx handler, so the rmnet packet processing itself
> happens in the same softirq when packets are queued to network stack
> by IPA.
This directly relates to the discussion about a WWAN subsystem that
Johannes Berg started a couple weeks ago. IPA appears to create a
netdev of its own. Is that netdev usable immediately, or does one need
to create an rmnet device on top to access the default PDN?
Thanks,
Dan
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next prev parent reply other threads:[~2019-06-03 14:50 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 [this message]
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
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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