linux-kernel - Re: [PATCH v2 0/2] i2c-designware: Add support for AMD PSP semaphore

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Date:   Fri, 28 Jan 2022 15:58:43 +0100
From:   Jan Dąbroś <jsd@...ihalf.com>
To:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Wolfram Sang <wsa@...nel.org>,
        Raul E Rangel <rrangel@...omium.org>,
        Marcin Wojtas <mw@...ihalf.com>,
        Grzegorz Jaszczyk <jaz@...ihalf.com>, upstream@...ihalf.com,
        Tom Lendacky <thomas.lendacky@....com>,
        "Deucher, Alexander" <alexander.deucher@....com>,
        "Easow, Nimesh" <Nimesh.Easow@....com>,
        "Limonciello, Mario" <mario.limonciello@....com>
Subject: Re: [PATCH v2 0/2] i2c-designware: Add support for AMD PSP semaphore

Hi,

Adding proper Andy's email address (and removing wrong one) in the
whole patchset. Sorry for noise!

Best Regards,
Jan


pt., 28 sty 2022 o 15:48 Jan Dabros <jsd@...ihalf.com> napisał(a):
>
> This patchset comprises support for new i2c-designware controller setup on some
> AMD Cezanne SoCs, where x86 is sharing i2c bus with PSP. PSP uses the same
> controller and acts as an i2c arbitrator there (x86 is leasing bus from it).
>
> First commit aims to improve generic i2c-designware code by adding extra locking
> on probe() and disable() paths. I would like to ask someone with access to
> boards which use Intel BayTrail(CONFIG_I2C_DESIGNWARE_BAYTRAIL) to verify
> behavior of my changes on such setup.
>
> Second commit adds support for new PSP semaphore arbitration mechanism.
> Implementation is similar to the one from i2c-designware-baytrail.c however
> there are two main differences:
> 1) Add new ACPI ID in order to protect against silent binding of the old driver
> to the setup with PSP semaphore. Extra flag ARBITRATION_SEMAPHORE added to this
> new _HID allows to recognize setup with PSP.
> 2) Beside acquire_lock() and release_lock() methods we are also applying quirks
> to the lock_bus() and unlock_bus() global adapter methods. With this in place
> all i2c clients drivers may lock i2c bus for a desired number of i2c
> transactions (e.g. write-wait-read) without being aware of that such bus is
> shared with another entity.
>
> This patchset is a follow-up to the RFC sent earlier on LKML [1], with review
> comments applied.
>
> Looking forward to some feedback.
>
> [1] https://lkml.org/lkml/2021/12/22/219
>
> v1 -> v2:
> * Remove usage of unions
> * Get rid of unnecessary __packed attributes
> * Switch to use iopoll.h and bitfields.h APIs were applicable
> * Follow the convention to check for the error first
> * Reorder entries (includes, table entries) alphabetically
> * Add necessary includes
> * Add Kconfig dependency on X86_64
> (above two fixes for "kernel test robot <lkp@...el.com>" issues)
> * Modify probe() to use terminating entry for traversing through table
>   instead of ARRAY_SIZE
> * Fix typos in comments
> * Rebase patchset
>
> Jan Dabros (2):
>   i2c: designware: Add missing locks
>   i2c: designware: Add AMD PSP I2C bus support
>
>  MAINTAINERS                                  |   1 +
>  drivers/acpi/acpi_apd.c                      |   7 +-
>  drivers/i2c/busses/Kconfig                   |  11 +
>  drivers/i2c/busses/Makefile                  |   1 +
>  drivers/i2c/busses/i2c-designware-amdpsp.c   | 373 +++++++++++++++++++
>  drivers/i2c/busses/i2c-designware-baytrail.c |  10 +-
>  drivers/i2c/busses/i2c-designware-common.c   |  12 +
>  drivers/i2c/busses/i2c-designware-core.h     |  18 +-
>  drivers/i2c/busses/i2c-designware-master.c   |   6 +
>  drivers/i2c/busses/i2c-designware-platdrv.c  |  61 +++
>  10 files changed, 489 insertions(+), 11 deletions(-)
>  create mode 100644 drivers/i2c/busses/i2c-designware-amdpsp.c
>
> --
> 2.35.0.rc0.227.g00780c9af4-goog
>