Re: [PATCH 0/4 v1] Mezzanine Low Speed connector bus

From: Frank Rowand <frowand.list@gmail.com>
To: Linus Walleij <linus.walleij@linaro.org>,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	dev@lists.96boards.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Michal Simek <michal.simek@xilinx.com>,
	Rob Herring <robh+dt@kernel.org>, Mark Brown <broonie@kernel.org>,
	John Stultz <john.stultz@linaro.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Andy Shevchenko <andy@infradead.org>
Subject: Re: [PATCH 0/4 v1] Mezzanine Low Speed connector bus
Date: Thu, 23 Aug 2018 16:06:00 -0700	[thread overview]
Message-ID: <cd3100ee-03a0-9218-b166-14f15d7669f6@gmail.com> (raw)
In-Reply-To: <20180823103332.32047-1-linus.walleij@linaro.org>

On 08/23/18 03:33, Linus Walleij wrote:
> I have been a bit hesitant to reiterate the series, but this is
> anyways a v1 of the 96Boards Mezzanine Low Speed connector
> driver framework.
> 
> I know the boards have a high speed connector as well, just
> trying to work stepwise and do the simple things first.
> 
> What convinced me to continue was very real usecases that exist
> today, as this makes the secure96 Mezzanine work:
> 
> - Get something upstream that makes it possible to without
>   any trouble or extensive ugly hacking probe and use the
>   secure96 mezzanine. This is motivated by the IoT design
>   space which needs a way to plug in proper security and the
>   secure96 offers a TPM chip for root of trust and key
>   handling.
> 
> - A clear indication that the same approach will work just
>   as fine with ACPI without reinventing the universe. I do
>   not have a definitive proof of this, but it is more
>   plausible that this will be reusable for ACPI than any of
>   the DT-centric ideas I've seen for populating
>   daughterboards. There are 96boards using ACPI today.
>   A secure96 TPM is desireable for things like the ARM
>   developer box which has this LS connector:
>   https://www.96boards.org/product/developerbox/
> 
> - Some indication that binding the connector like this will
>   not implicate or screw things up for the DT-overlays
>   idea, i.e. a both/and and not either/or approach.
> 
> The idea is for this to go upstream through ARM SoC the day
> noone actively NACK it and someone actively ACK it. Expect
> some more iterations.
> 
> Linus Walleij (4):
>   eeprom: at24: Allow passing gpiodesc from pdata
>   spi: Make of_find_spi_device_by_node() available
>   bus: Add DT bindings for 96Boards low speed connector
>   bus: 96boards Low-Speed Connector

For the moment, NACK since there is not a substantive change
from before.  This is without having read beyond this
introduction.

I will read through the rest of the series and revisit my
previous conclusions, but most likely not for a few days.

-Frank

> 
>  .../bus/96boards,low-speed-connector.txt      |  50 +++
>  drivers/bus/Kconfig                           |   2 +
>  drivers/bus/Makefile                          |   4 +-
>  drivers/bus/daughterboards/96boards-ls-bus.c  |  39 ++
>  .../daughterboards/96boards-ls-connector.c    | 367 ++++++++++++++++++
>  .../bus/daughterboards/96boards-mezzanines.h  |  77 ++++
>  .../bus/daughterboards/96boards-secure96.c    | 265 +++++++++++++
>  drivers/bus/daughterboards/Kconfig            |  50 +++
>  drivers/bus/daughterboards/Makefile           |   6 +
>  drivers/misc/eeprom/at24.c                    |   6 +-
>  drivers/spi/spi.c                             |  33 +-
>  include/linux/platform_data/at24.h            |   2 +
>  include/linux/spi/spi.h                       |   4 +
>  13 files changed, 888 insertions(+), 17 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/bus/96boards,low-speed-connector.txt
>  create mode 100644 drivers/bus/daughterboards/96boards-ls-bus.c
>  create mode 100644 drivers/bus/daughterboards/96boards-ls-connector.c
>  create mode 100644 drivers/bus/daughterboards/96boards-mezzanines.h
>  create mode 100644 drivers/bus/daughterboards/96boards-secure96.c
>  create mode 100644 drivers/bus/daughterboards/Kconfig
>  create mode 100644 drivers/bus/daughterboards/Makefile
> 