Re: [PATCH v5 4/6] reset: Instantiate reset GPIO controller for shared reset-gpios

[Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>]

On 24/01/2024 08:45, Krzysztof Kozlowski wrote:
> Devices sharing a reset GPIO could use the reset framework for
> coordinated handling of that shared GPIO line.  We have several cases of
> such needs, at least for Devicetree-based platforms.
> 
> If Devicetree-based device requests a reset line, while "resets"
> Devicetree property is missing but there is a "reset-gpios" one,
> instantiate a new "reset-gpio" platform device which will handle such
> reset line.  This allows seamless handling of such shared reset-gpios
> without need of changing Devicetree binding [1].
> 
> To avoid creating multiple "reset-gpio" platform devices, store the
> Devicetree "reset-gpios" GPIO specifiers used for new devices on a
> linked list.  Later such Devicetree GPIO specifier (phandle to GPIO
> controller, GPIO number and GPIO flags) is used to check if reset
> controller for given GPIO was already registered.
> 
> If two devices have conflicting "reset-gpios" property, e.g. with
> different ACTIVE_xxx flags, this would allow to spawn two separate
> "reset-gpio" devices, where the second would fail probing on busy GPIO
> request.
> 
> Link: https://lore.kernel.org/all/YXi5CUCEi7YmNxXM@xxxxxxxxxxxxxxxxxx/ [1]
> Cc: Bartosz Golaszewski <brgl@xxxxxxxx>
> Cc: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
> Cc: Sean Anderson <sean.anderson@xxxxxxxx>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> 
> ---
> 
> Depends on previous of change.
> ---
>  drivers/reset/core.c             | 215 +++++++++++++++++++++++++++++--
>  include/linux/reset-controller.h |   4 +
>  2 files changed, 206 insertions(+), 13 deletions(-)
> 

LKP reported issue when building !GPIOLIB:
https://lore.kernel.org/oe-kbuild-all/202401250958.YksQmnWj-lkp@xxxxxxxxx/

but I intend to solve it providing the stubs. Therefore this patch will
not change.

Best regards,
Krzysztof