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Subject: Re: [PATCH v4 0/8] Introduce intel_skl_int3472 module
To:     Daniel Scally <djrscally@gmail.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Wolfram Sang <wsa@kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Maximilian Luz <luzmaximilian@gmail.com>,
        linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org,
        linux-i2c@vger.kernel.org, platform-driver-x86@vger.kernel.org,
        devel@acpica.org
Cc:     Len Brown <lenb@kernel.org>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Russell King <linux@armlinux.org.uk>,
        Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Mark Gross <mgross@linux.intel.com>,
        Robert Moore <robert.moore@intel.com>,
        Erik Kaneda <erik.kaneda@intel.com>,
        laurent.pinchart@ideasonboard.com, kieran.bingham@ideasonboard.com
References: <20210520140928.3252671-1-djrscally@gmail.com>
From:   Hans de Goede <hdegoede@redhat.com>
Message-ID: <f2d8e74f-f33b-2489-1b90-b11bf7465d19@redhat.com>
Date:   Tue, 25 May 2021 15:10:34 +0200
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Hi Daniel,

On 5/20/21 4:09 PM, Daniel Scally wrote:
> Hello all
> 
> Apologies for the long delay since the last version of this series; the time I
> had free to work on it became somewhat restrained.

No worries, thank you for all the work you are putting into this.

I have not taken a close look at the code yet, but I see that Andy has and
the amount of remarks which he has on patch 7/8 which is the big one seems
to be limited, so I believe that we are getting close to this being ready
for merging.

This touches a lot of subsystems, so we need to come up with a plan to
merge this. Here is my proposal for how to do this:

1/8   ACPI: scan: Extend acpi_walk_dep_device_list()
2/8   ACPI: scan: Add function to fetch dependent of acpi device
3/8   i2c: core: Add a format macro for I2C device names
4/8   gpiolib: acpi: Export acpi_get_gpiod()
5/8   clkdev: Make clkdev_drop() null aware
6/8   gpiolib: acpi: Add acpi_gpio_get_io_resource()
7/8   platform/x86: Add intel_skl_int3472 driver
8/8   mfd: tps68470: Remove tps68470 MFD driver

Rafael already indicated that he wants to merge 1/8 (and presumably also 2/8)
through his tree and that he will provide an immutable branch with those
for merging into the pdx86 tree.

4/8 and 6/8 are both gpiolib-acpi patches and seem to be ready for merging
now, perhaps the gpiolib-acpi maintainers can already merge these and also
provide an immutable branch ?  Andy/Mika ?

3/8 and 5/8 seem to be nice cleanups, but not really necessary. IMHO it
would be best to park these cleanups for later and for 3/8 add the following
where necessary for now:

/* FIXME drop this once the I2C_DEV_NAME_FORMAT macro has been added to include/linux/i2c.h */
#ifndef I2C_DEV_NAME_FORMAT
#define I2C_DEV_NAME_FORMAT		"i2c-%s"
#endif

This is not the prettiest but it reduces all the subsys cross-deps and things
like this have been done before for similar reasons.

Likewise it would be good if you can add if (foo) as condition before any
clkdev_drop(foo) calls in this patch-set and then merge
5/8 "clkdev: Make clkdev_drop() null aware" independently of this and then
once both are in Linux tree follow-up with a cleanup patch dropping the if (foo)
guards.

So this would leave as deps for 7/8 just the 2 ACPI and 2 gpiolib-acpi patches
which I can hopefully pull-in via immutable branches and then we are good.

AFAICT patch 8/8 can be merged independently once 7/8 hits for-next (IOW once
we are sure the next kernel will have 7/8).


Or alternatively one of the involved subsys maintainers just merges the entire
set (once it is ready) and then provides an immutable branch with the entire set
on top of 5.13-rc1 (or 5.14-rc1). But that requires acks from all the other
subsys maintainers. Note I'm fine with either approach.

Regards,

Hans


> v1 for this series was originally 14-18 of this series:
> https://lore.kernel.org/linux-media/20201130133129.1024662-1-djrscally@gmail.com/T/#m91934e12e3d033da2e768e952ea3b4a125ee3e67
> 
> v2 was here:
> https://lore.kernel.org/platform-driver-x86/20210118003428.568892-1-djrscally@gmail.com/
> 
> v3 was here:
> https://lore.kernel.org/lkml/20210222130735.1313443-1-djrscally@gmail.com/
> 
> Series level changelog:
> 
> 	- Added patch 5/8 to make clkdev_drop() NULL aware to simplify error
> 	handling.
> 	- Added patch 6/8 to add acpi_gpio_get_io_resource().
> 
> This has been tested on a number of devices, but currently **not** on a device
> designed for ChromeOS, which we ideally need to do to ensure no regression
> caused by replacing the tps68470 MFD driver. Unfortunately, I don't have a
> device to test it on myself.
> 
> =========== Original Cover Letter ===========
> 
> At the moment in the kernel the ACPI _HID INT3472 is taken by the tps68470
> MFD driver, but that driver can only handle some of the cases of that _HID
> that we see. There are at least these three possibilities:
> 
> 1. INT3472 devices that provide GPIOs through the usual framework and run
>    power and clocks through an operation region; this is the situation that
>    the current module handles and is seen on ChromeOS devices
> 2. INT3472 devices that provide GPIOs, plus clocks and regulators that are
>    meant to be driven through the usual frameworks, usually seen on devices
>    designed to run Windows
> 3. INT3472 devices that don't actually represent a physical tps68470, but
>    are being used as a convenient way of grouping a bunch of system GPIO
>    lines that are intended to enable power and clocks for sensors which
>    are called out as dependent on them. Also seen on devices designed to
>    run Windows.
> 
> This series introduces a new module which registers:
> 
> 1. An i2c driver that determines which scenario (#1 or #2) applies to the
>    machine and registers platform devices to be bound to GPIO, OpRegion,
>    clock and regulator drivers as appropriate.
> 2. A platform driver that binds to the dummy INT3472 devices described in
>    #3
> 
> The platform driver for the dummy device registers the GPIO lines that
> enable the clocks and regulators to the sensors via those frameworks so
> that sensor drivers can consume them in the usual fashion. The existing
> GPIO and OpRegion tps68470 drivers will work with the i2c driver that's
> registered. Clock and regulator drivers are available but have not so far been
> tested, so aren't part of this series.
> 
> The existing mfd/tps68470.c driver being thus superseded, it is removed.
> 
> Thanks
> Dan
> 
> Daniel Scally (8):
>   ACPI: scan: Extend acpi_walk_dep_device_list()
>   ACPI: scan: Add function to fetch dependent of acpi device
>   i2c: core: Add a format macro for I2C device names
>   gpiolib: acpi: Export acpi_get_gpiod()
>   clkdev: Make clkdev_drop() null aware
>   gpiolib: acpi: Add acpi_gpio_get_io_resource()
>   platform/x86: Add intel_skl_int3472 driver
>   mfd: tps68470: Remove tps68470 MFD driver
> 
>  MAINTAINERS                                   |   5 +
>  drivers/acpi/ec.c                             |   2 +-
>  drivers/acpi/pmic/Kconfig                     |   2 +-
>  drivers/acpi/pmic/intel_pmic_chtdc_ti.c       |   2 +-
>  drivers/acpi/scan.c                           | 107 ++++-
>  drivers/clk/clkdev.c                          |   3 +
>  drivers/gpio/Kconfig                          |   2 +-
>  drivers/gpio/gpiolib-acpi.c                   |  61 ++-
>  drivers/i2c/i2c-core-acpi.c                   |   8 +-
>  drivers/i2c/i2c-core-base.c                   |   4 +-
>  drivers/mfd/Kconfig                           |  18 -
>  drivers/mfd/Makefile                          |   1 -
>  drivers/mfd/tps68470.c                        |  97 -----
>  drivers/platform/surface/aggregator/core.c    |   6 +-
>  drivers/platform/surface/surface3_power.c     |  22 +-
>  .../platform/surface/surface_acpi_notify.c    |   7 +-
>  drivers/platform/x86/Kconfig                  |   2 +
>  drivers/platform/x86/Makefile                 |   1 +
>  drivers/platform/x86/intel-int3472/Kconfig    |  31 ++
>  drivers/platform/x86/intel-int3472/Makefile   |   5 +
>  .../intel_skl_int3472_clk_and_regulator.c     | 195 +++++++++
>  .../intel-int3472/intel_skl_int3472_common.c  | 106 +++++
>  .../intel-int3472/intel_skl_int3472_common.h  | 113 +++++
>  .../intel_skl_int3472_discrete.c              | 409 ++++++++++++++++++
>  .../intel_skl_int3472_tps68470.c              | 109 +++++
>  include/acpi/acpi_bus.h                       |   8 +
>  include/linux/acpi.h                          |  11 +-
>  include/linux/gpio/consumer.h                 |   2 +
>  include/linux/i2c.h                           |   3 +
>  29 files changed, 1175 insertions(+), 167 deletions(-)
>  delete mode 100644 drivers/mfd/tps68470.c
>  create mode 100644 drivers/platform/x86/intel-int3472/Kconfig
>  create mode 100644 drivers/platform/x86/intel-int3472/Makefile
>  create mode 100644 drivers/platform/x86/intel-int3472/intel_skl_int3472_clk_and_regulator.c
>  create mode 100644 drivers/platform/x86/intel-int3472/intel_skl_int3472_common.c
>  create mode 100644 drivers/platform/x86/intel-int3472/intel_skl_int3472_common.h
>  create mode 100644 drivers/platform/x86/intel-int3472/intel_skl_int3472_discrete.c
>  create mode 100644 drivers/platform/x86/intel-int3472/intel_skl_int3472_tps68470.c
>