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From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: "Enrico Weigelt, metux IT consult" <lkml@metux.net>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	"Enrico Weigelt, metux IT consult" <info@metux.net>,
	Viresh Kumar <vireshk@kernel.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Bill Mills <bill.mills@linaro.org>,
	Alex Benn?e <alex.bennee@linaro.org>,
	stratos-dev@op-lists.linaro.org,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	"Stefano Garzarella --cc virtualization @ lists .
	linux-foundation . org"  <sgarzare@redhat.com>,
	virtualization@lists.linux-foundation.org,
	Alistair Strachan <astrachan@google.com>
Subject: Re: [PATCH V3 1/3] gpio: Add virtio-gpio driver
Date: Mon, 21 Jun 2021 12:25:28 -0500	[thread overview]
Message-ID: <YNDLiPYkmLZN076t@yoga> (raw)
In-Reply-To: <8d58da79-8e54-048b-db89-8c1caaa0320f@metux.net>

On Wed 16 Jun 10:52 CDT 2021, Enrico Weigelt, metux IT consult wrote:

> On 16.06.21 05:30, Bjorn Andersson wrote:
> 
> > Combined with the virtio-i2c effort this could provide an alternative by
> > simply tunneling the busses and GPIOs into Linux and use standard iio
> > drivers, for cases where this suits your product requirements better.
> 
> So, you wanna use virtio as logical interface between the two CPUs ?
> Interesting idea. Usually folks use rpmsg for those things.
> 

rpmsg is a layer on top of virtio, so this would be an extension of the
existing model.

There's been discussions (and I believe some implementations) related to
bridging I2C requests over rpmsg, but I think it's preferable to
standardize around the virtio based bearer directly.

> What is running on the secondary CPU ? Some OS like Linux or some bare
> metal stuff ? What kind of CPU is that anyways ?
> 

These ideas revolves around platforms that implements something like the
"Android Sensor Hub", which provides some resource constraint
co-processor that deals with sensor device interaction and processing of
the data without waking up the power-hungry ARM cores.

Given the focus on power consumption I would guess that these are not
going to run Linux. Core-wise I've seen this implemented using primarily
ARM and Hexagon cores.

Regards,
Bjorn

WARNING: multiple messages have this Message-ID (diff)
From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: "Enrico Weigelt, metux IT consult" <lkml@metux.net>
Cc: Alistair Strachan <astrachan@google.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	virtualization@lists.linux-foundation.org,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Viresh Kumar <vireshk@kernel.org>,
	stratos-dev@op-lists.linaro.org, "Enrico Weigelt,
	metux IT consult" <info@metux.net>,
	Bill Mills <bill.mills@linaro.org>
Subject: Re: [PATCH V3 1/3] gpio: Add virtio-gpio driver
Date: Mon, 21 Jun 2021 12:25:28 -0500	[thread overview]
Message-ID: <YNDLiPYkmLZN076t@yoga> (raw)
In-Reply-To: <8d58da79-8e54-048b-db89-8c1caaa0320f@metux.net>

On Wed 16 Jun 10:52 CDT 2021, Enrico Weigelt, metux IT consult wrote:

> On 16.06.21 05:30, Bjorn Andersson wrote:
> 
> > Combined with the virtio-i2c effort this could provide an alternative by
> > simply tunneling the busses and GPIOs into Linux and use standard iio
> > drivers, for cases where this suits your product requirements better.
> 
> So, you wanna use virtio as logical interface between the two CPUs ?
> Interesting idea. Usually folks use rpmsg for those things.
> 

rpmsg is a layer on top of virtio, so this would be an extension of the
existing model.

There's been discussions (and I believe some implementations) related to
bridging I2C requests over rpmsg, but I think it's preferable to
standardize around the virtio based bearer directly.

> What is running on the secondary CPU ? Some OS like Linux or some bare
> metal stuff ? What kind of CPU is that anyways ?
> 

These ideas revolves around platforms that implements something like the
"Android Sensor Hub", which provides some resource constraint
co-processor that deals with sensor device interaction and processing of
the data without waking up the power-hungry ARM cores.

Given the focus on power consumption I would guess that these are not
going to run Linux. Core-wise I've seen this implemented using primarily
ARM and Hexagon cores.

Regards,
Bjorn
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

  parent reply	other threads:[~2021-06-21 17:25 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-10 12:09 [PATCH V3 0/3] gpio: Add virtio based driver Viresh Kumar
2021-06-10 12:09 ` Viresh Kumar
2021-06-10 12:16 ` [PATCH V3 1/3] gpio: Add virtio-gpio driver Viresh Kumar
2021-06-10 12:16   ` Viresh Kumar
2021-06-10 13:22   ` Arnd Bergmann
2021-06-10 16:00     ` Enrico Weigelt, metux IT consult
     [not found]     ` <01000179f6a7715c-cd106846-7770-4088-bb7c-a696bfcbf83e-000000@email.amazonses.com>
2021-06-10 17:03       ` [Stratos-dev] " Jean-Philippe Brucker
2021-06-10 17:03         ` Jean-Philippe Brucker
2021-06-10 19:41         ` Arnd Bergmann
2021-06-14 10:21     ` Viresh Kumar
2021-06-14 10:21       ` Viresh Kumar
2021-06-14 12:31       ` Arnd Bergmann
2021-06-14 12:49         ` Vincent Guittot
     [not found]         ` <0100017a0a9264cc-57668c56-fdbf-412a-9f82-9bf95f5c653e-000000@email.amazonses.com>
2021-06-14 12:58           ` [Stratos-dev] " Arnd Bergmann
2021-06-14 13:24             ` Vincent Guittot
2021-06-14 20:54               ` Arnd Bergmann
2021-06-15  7:30                 ` Vincent Guittot
2021-06-10 15:54   ` Enrico Weigelt, metux IT consult
2021-06-10 16:57     ` Viresh Kumar
2021-06-10 16:57       ` Viresh Kumar
2021-06-10 20:46   ` Linus Walleij
2021-06-10 20:46     ` Linus Walleij
2021-06-11  3:56     ` Viresh Kumar
2021-06-11  3:56       ` Viresh Kumar
2021-06-11  7:42       ` Geert Uytterhoeven
2021-06-11  7:42         ` Geert Uytterhoeven
2021-06-11  8:01         ` Viresh Kumar
2021-06-11  8:01           ` Viresh Kumar
2021-06-11  8:22           ` Geert Uytterhoeven
2021-06-11  8:22             ` Geert Uytterhoeven
2021-06-15 11:15             ` Viresh Kumar
2021-06-15 11:15               ` Viresh Kumar
2021-06-15 11:37               ` Geert Uytterhoeven
2021-06-15 11:37                 ` Geert Uytterhoeven
2021-06-15 20:03               ` Linus Walleij
2021-06-15 20:03                 ` Linus Walleij
2021-06-16  1:45                 ` Viresh Kumar
2021-06-16  1:45                   ` Viresh Kumar
2021-06-14  8:07           ` Enrico Weigelt, metux IT consult
2021-06-14  8:12             ` Andy Shevchenko
2021-06-14  8:12               ` Andy Shevchenko
2021-06-14  9:14               ` Viresh Kumar
2021-06-14  9:14                 ` Viresh Kumar
2021-06-14  9:17               ` Enrico Weigelt, metux IT consult
2021-06-14  9:52                 ` Viresh Kumar
2021-06-14  9:52                   ` Viresh Kumar
2021-06-14  9:12             ` Viresh Kumar
2021-06-14  9:12               ` Viresh Kumar
2021-06-14  9:29               ` Enrico Weigelt, metux IT consult
2021-06-14  8:03         ` Enrico Weigelt, metux IT consult
2021-06-14  9:24           ` Viresh Kumar
2021-06-14  9:24             ` Viresh Kumar
2021-06-16  3:30     ` Bjorn Andersson
2021-06-16  3:30       ` Bjorn Andersson
2021-06-16 15:52       ` Enrico Weigelt, metux IT consult
2021-06-18  9:13         ` Linus Walleij
2021-06-18  9:13           ` Linus Walleij
2021-06-21 17:25         ` Bjorn Andersson [this message]
2021-06-21 17:25           ` Bjorn Andersson
2021-06-10 12:16 ` [PATCH V3 2/3] gpio: virtio: Add IRQ support Viresh Kumar
2021-06-10 12:16   ` Viresh Kumar
2021-06-10 21:30   ` Linus Walleij
2021-06-10 21:30     ` Linus Walleij
2021-06-14  7:08     ` Viresh Kumar
2021-06-14  7:08       ` Viresh Kumar
2021-06-10 12:16 ` [PATCH V3 3/3] MAINTAINERS: Add entry for Virtio-gpio Viresh Kumar
     [not found] ` <01000179f5da7763-2ea817c6-e176-423a-952e-de02443f71e2-000000@email.amazonses.com>
2021-06-10 17:40   ` [PATCH V3 1/3] gpio: Add virtio-gpio driver Jean-Philippe Brucker
2021-06-10 17:40     ` Jean-Philippe Brucker
2021-06-11  3:39     ` Viresh Kumar
2021-06-11  3:39       ` Viresh Kumar
     [not found]     ` <01000179f9276678-ae2bb25f-4c0c-4176-b906-650c585b9753-000000@email.amazonses.com>
2021-06-11  8:34       ` [Stratos-dev] " Arnd Bergmann
2021-06-14  5:26         ` Viresh Kumar
2021-06-14  5:26           ` Viresh Kumar

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