Re: [PATCH] gpio: Drop CONFIG_DEBUG_GPIO

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Fri, Mar 11, 2022 at 12:09 AM Brian Norris <briannorris@xxxxxxxxxxxx> wrote:
>
> CONFIG_DEBUG_GPIO has existed since the introduction of gpiolib, but its
> Kconfig description and motivation seem to have been off-base for quite
> some time.
>
> Description: it says nothing about enabling extra printk()s. But -DDEBUG
> does just that; it turns on every dev_dbg()/pr_debug() that would
> otherwise be silent.
>
> Purpose: might_sleep() and WARN_ON() should have very low overhead, and
> anyway, there's a separate CONFIG_DEBUG_ATOMIC_SLEEP for the
> might_sleep() overhead.
>
> Additionally, the conflated purpose (extra debug checks, and extra
> printing) makes for a mixed bag for users. In particular, some drivers
> can be extra-spammy with -DDEBUG -- e.g., with the Rockchip GPIO driver
> getting moved out of drivers/pinctrl/ in commit 936ee2675eee
> ("gpio/rockchip: add driver for rockchip gpio"), now some dev_dbg()
> calls are enabled in its IRQ handler.
>
> Altogether, it seems like CONFIG_DEBUG_GPIO isn't serving any good
> purpose and should just be removed. It can be supplanted by dynamic
> debug (which post-dates gpiolib) and atomic-debug facilities.
>
> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
> ---
>

I like it. It's true we don't see many of those DEBUG constructs
anymore nowadays and overhead for might_sleep() and WARN_ON() is
negligible.

Applied, thanks!

Bart