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Date: Mon, 18 Jul 2022 10:48:11 +0000
From: Tzung-Bi Shih <tzungbi@kernel.org>
To: Guenter Roeck <groeck@google.com>
Cc: Benson Leung <bleung@chromium.org>, Guenter Roeck <groeck@chromium.org>,
	"open list:CHROME HARDWARE PLATFORM SUPPORT" <chrome-platform@lists.linux.dev>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	kernel test robot <lkp@intel.com>
Subject: Re: [PATCH] platform/chrome: cros_kbd_led_backlight: fix build
 warning
Message-ID: <YtU6a+bIpgpyScsL@google.com>
References: <20220718061608.2303425-1-tzungbi@kernel.org>
 <CABXOdTeH-q=17QBnCn5NGT5V0QA5SOaTnrWaK+g5F3j4mVp8cA@mail.gmail.com>
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In-Reply-To: <CABXOdTeH-q=17QBnCn5NGT5V0QA5SOaTnrWaK+g5F3j4mVp8cA@mail.gmail.com>

On Sun, Jul 17, 2022 at 11:54:31PM -0700, Guenter Roeck wrote:
> On Sun, Jul 17, 2022 at 11:16 PM Tzung-Bi Shih <tzungbi@kernel.org> wrote:
> >
> > drivers/platform/chrome/cros_kbd_led_backlight.c got a new build warning
> > when using the randconfig in [1]:
> > >>> warning: unused variable 'keyboard_led_drvdata_ec_pwm'
> >
> > The warning happens when CONFIG_CROS_EC is set but CONFIG_OF is not set.
> > Reproduce:
> > - mkdir build_dir
> > - wget [1] -O build_dir/.config
> > - COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 \
> >   O=build_dir ARCH=s390 SHELL=/bin/bash drivers/platform/chrome/
> >
> 
> Have you tried the following ?
>     CONFIG_ACPI=y
>     CONFIG_CROS_EC=n
>     CONFIG_OF=y
> 
> That should be possible, but with your patch it should now result in a
> build error because keyboard_led_drvdata_ec_pwm is no longer defined.

Hmm, just got another lkp robot's warning about the undeclared symbol.  Will
fix it by using __maybe_unused in next version.

> Also, with your patch, CONFIG_CROS_EC=y, CONFIG_ACPI=y, and
> CONFIG_OF=n (ie Intel/AMD systems) would result in the code not being
> compiled, which would be wrong.

Intel and AMD systems rely on `keyboard_led_drvdata_acpi` but not
`keyboard_led_drvdata_ec_pwm` for now.  They shouldn't be affected by the
patch.

In any cases, let's use __maybe_unused in next version.