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SubjectRE: [PATCH v2 00/22] mfd: demodularization of non-modular drivers
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Hi Paul,

On 03 December 2018 04:23, Paul Gortmaker wrote:

> Subject: [PATCH v2 00/22] mfd: demodularization of non-modular drivers
>
> [v1 --> v2: add some more commits as requested by Lee (MFD maintainer),
> update the 00/NN text; re-do build and link testing on new linux-next. ]
>
> This group of MFD drivers are all controlled by "bool" Kconfig settings,
> but contain various amounts of largely pointless uses of infrastructure
> related to modular operations, even though they can't be built modular.
>
> We can easily remove/replace all of it. We are trying to make driver
> code consistent with the Makefiles/Kconfigs that control them.

For the DA9052 and DA9055, changes:

- drivers/mfd/da9052-core.c | 11 -----------
- drivers/mfd/da9052-i2c.c | 22 ++-------------------
- drivers/mfd/da9052-irq.c | 1 -
- drivers/mfd/da9052-spi.c | 22 ++-------------------
- drivers/mfd/da9055-core.c | 13 ++-----------
- drivers/mfd/da9055-i2c.c | 24 ++---------------------

The responsibility can fall back to Dialog for these changes. We will
submit Kconfig patches for these and make them explicitly non-modular.
This will remove the ambiguity caused by the Kconfig bool options.

Regards,
Steve

> This
> means not using modular functions/macros for drivers that can never be
> built as a module. Some of the downfalls this oversight leads to are:
>
> (1) it is easy to accidentally write unused module_exit and remove code
> (2) it can be misleading when reading the source, thinking it can be
> modular when the Makefile and/or Kconfig prohibit it
> (3) it requires the include of the module.h header file which in turn
> includes nearly everything else, thus adding a lot of CPP overhead.
> (4) it gets copied/replicated into other drivers and spreads quickly.
>
> What we see in current drivers falls into one or more of the following
> categories:
>
> 1) include of <linux/module.h> when it simply isn't needed
>
> 2) Use of MODULE_LICENSE, MODULE_DEVICE_TABLE, MODULE_AUTHOR etc.
> macros that are no-ops for non-modular drivers.
>
> 3) Creation of a module_exit() function that will be compiled and
> linked in but never actually called for non-modular drivers.
>
> 4) Addition of a platform_driver ".remove" function that is bound
> into the struct but will never be called for non-module use cases.
>
> Solution to #1 --> #3 is simple ; we just delete the related code.
>
> The solution to #4 is similar - we delete the ".remove" function and
> the binding into the platform_driver struct. However, since the same
> ".remove" function could also be triggered by an "unbind" (such as for
> pass-through of a device to a guest instance) - so we also explicitly
> disable any unbind for the driver.
>
> The unbind mask allows us to ensure we will see if there was some odd
> corner case out there that was relying on it. Typically it would be a
> multi-port ethernet card passing a port through to a guest, so a
> sensible use case in MFD drivers seems highly unlikely. This same
> solution has already been used in multiple other mainline subsystems.
>
> Build testing was done on drivers/mfd for allyesconfig on x86_64, ARM
> and ARM-64 on a recent linux-next checkout.
>
> Paul.
>
> ---
>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Cory Maccarrone <darkstar6262@gmail.com>
> Cc: David Dajun Chen <dchen@diasemi.com>
> Cc: Dong Aisheng <dong.aisheng@linaro.org>
> Cc: Eric Miao <eric.miao@marvell.com>
> Cc: Graeme Gregory <gg@slimlogic.co.uk>
> Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> Cc: Haojian Zhuang <haojian.zhuang@marvell.com>
> Cc: Jin Park <jinyoungp@nvidia.com>
> Cc: Jorge Eduardo Candelaria <jedu@slimlogic.co.uk>
> Cc: Laxman Dewangan <ldewangan@nvidia.com>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
> Cc: Mattias Nilsson <mattias.i.nilsson@stericsson.com>
> Cc: Michael Hennerich <michael.hennerich@analog.com>
> Cc: Mike Rapoport <mike@compulab.co.il>
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Venu Byravarasu <vbyravarasu@nvidia.com>
> Cc: linux-omap@vger.kernel.org
> Cc: patches@opensource.cirrus.com
> Cc: Support Opensource <support.opensource@diasemi.com>
>
>
> Paul Gortmaker (22):
> mfd: aat2870-core: Make it explicitly non-modular
> mfd: adp5520: Make it explicitly non-modular
> mfd: as3711: Make it explicitly non-modular
> mfd: da903x: Make it explicitly non-modular
> mfd: da9052-*: Make it explicitly non-modular
> mfd: da9055-i2c: Make it explicitly non-modular
> mfd: da9055-core: make it explicitly non-modular
> mfd: db8500-prcmu: drop unused MODULE_ tags from non-modular code
> mfd: htc-i2cpld: Make it explicitly non-modular
> mfd: max8925-core: drop unused MODULE_ tags from non-modular code
> mfd: rc5t583: Make it explicitly non-modular
> mfd: sta2x11: drop unused MODULE_ tags from non-modular code
> mfd: syscon: Make it explicitly non-modular
> mfd: tps65090: Make it explicitly non-modular
> mfd: tps65910: Make it explicitly non-modular
> mfd: tps80031: Make it explicitly non-modular
> mfd: wm831x-spi: Make it explicitly non-modular
> mfd: wm831x-i2c: Make it explicitly non-modular
> mfd: wm831x-core: drop unused MODULE_ tags from non-modular code
> mfd: wm8350-i2c: Make it explicitly non-modular
> mfd: wm8350-core: drop unused MODULE_ tags from non-modular code
> mfd: wm8400-core: Make it explicitly non-modular
>
> drivers/mfd/aat2870-core.c | 40 +++------------------------------------
> drivers/mfd/adp5520.c | 30 +++++++----------------------
> drivers/mfd/as3711.c | 14 --------------
> drivers/mfd/da903x.c | 26 +++----------------------
> drivers/mfd/da9052-core.c | 11 -----------
> drivers/mfd/da9052-i2c.c | 22 ++-------------------
> drivers/mfd/da9052-irq.c | 1 -
> drivers/mfd/da9052-spi.c | 22 ++-------------------
> drivers/mfd/da9055-core.c | 13 ++-----------
> drivers/mfd/da9055-i2c.c | 24 ++---------------------
> drivers/mfd/db8500-prcmu.c | 10 ++++------
> drivers/mfd/htc-i2cpld.c | 18 +-----------------
> drivers/mfd/max8925-core.c | 7 +------
> drivers/mfd/rc5t583.c | 14 --------------
> drivers/mfd/sta2x11-mfd.c | 10 ++++------
> drivers/mfd/syscon.c | 12 +-----------
> drivers/mfd/tps65090.c | 30 +++++------------------------
> drivers/mfd/tps65910.c | 18 +-----------------
> drivers/mfd/tps80031.c | 37 ++----------------------------------
> drivers/mfd/wm831x-core.c | 7 ++-----
> drivers/mfd/wm831x-i2c.c | 20 ++------------------
> drivers/mfd/wm831x-spi.c | 24 ++---------------------
> drivers/mfd/wm8350-core.c | 6 ++----
> drivers/mfd/wm8350-i2c.c | 24 +----------------------
> drivers/mfd/wm8400-core.c | 18 +++---------------
> include/linux/mfd/da9052/da9052.h | 1 -
> 26 files changed, 52 insertions(+), 407 deletions(-)
>
> --
> 2.7.4

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