Re: [PATCH v2 1/2] pwm: rcar: drop of_match_ptr for ID table - Uwe Kleine-König

From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	Fabrice Gasnier <fabrice.gasnier@foss.st.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 1/2] pwm: rcar: drop of_match_ptr for ID table
Date: Sun, 12 Mar 2023 16:42:10 +0100	[thread overview]
Message-ID: <20230312154210.ovm54x2qtcv7fp7r@pengutronix.de> (raw)
In-Reply-To: <20230312135120.357713-1-krzysztof.kozlowski@linaro.org>

[-- Attachment #1: Type: text/plain, Size: 2020 bytes --]

Hello,

On Sun, Mar 12, 2023 at 02:51:19PM +0100, Krzysztof Kozlowski wrote:
> The driver can match only via the DT table so the table should be always
> used and the of_match_ptr does not have any sense (this also allows ACPI
> matching via PRP0001, even though it might not be relevant here).  This
> also fixes !CONFIG_OF error:
> 
>   drivers/pwm/pwm-rcar.c:252:34: error: ‘rcar_pwm_of_table’ defined but not used [-Werror=unused-const-variable=]
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Hmm, I wonder what else is required here to trigger that warning. On
amd64 I also disabled CONFIG_MODULES as otherwise rcar_pwm_of_table is
used by

	MODULE_DEVICE_TABLE(of, rcar_pwm_of_table);

With that I have:

	uwe@taurus:~/work/kbuild/amd64$ make drivers/pwm/pwm-rcar.o 
	  GEN     Makefile
	  CALL    /home/uwe/gsrc/linux/scripts/checksyscalls.sh
	  DESCEND objtool
	  INSTALL libsubcmd_headers
	  CC      drivers/pwm/pwm-rcar.o
	uwe@taurus:~/work/kbuild/amd64$ make drivers/pwm/pwm-rcar.i
	  GEN     Makefile
	  CALL    /home/uwe/gsrc/linux/scripts/checksyscalls.sh
	  DESCEND objtool
	  INSTALL libsubcmd_headers
	  CPP     drivers/pwm/pwm-rcar.i
	uwe@taurus:~/work/kbuild/amd64$ grep rcar_pwm_of_table drivers/pwm/pwm-rcar.i
	static const struct of_device_id rcar_pwm_of_table[] = {

... some time later ...

ah, you also need W=1 to get that warning because of

	# These warnings generated too much noise in a regular build.
	# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
	KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
	KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)

in the toplevel Makefile.

I guess that explains why there is no previous report by one of the
build bots about this issue.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]