linux-kernel - Re: [PATCH] soc: rockchip: work around clang warning

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Message-ID: <20190704022043.gwcwasi6jni2qctm@localhost>
Date:   Wed, 3 Jul 2019 19:20:43 -0700
From:   Olof Johansson <olof@...om.net>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Heiko Stuebner <heiko@...ech.de>, arm@...nel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] soc: rockchip: work around clang warning

On Wed, Jul 03, 2019 at 05:30:59PM +0200, Arnd Bergmann wrote:
> clang emits a warning about a negative shift count for an
> unused part of a conditional constant expression:
> 
> drivers/soc/rockchip/pm_domains.c:795:21: error: shift count is negative [-Werror,-Wshift-count-negative]
>         [RK3328_PD_VIO]         = DOMAIN_RK3328(-1, 8, 8, false),
>                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/soc/rockchip/pm_domains.c:129:2: note: expanded from macro 'DOMAIN_RK3328'
>         DOMAIN_M(pwr, pwr, req, (req) + 10, req, wakeup)
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/soc/rockchip/pm_domains.c:105:33: note: expanded from macro 'DOMAIN_M'
>         .status_mask = (status >= 0) ? BIT(status) : 0, \
>                                        ^~~~~~~~~~~
> include/linux/bits.h:6:24: note: expanded from macro 'BIT'
> 
> This is a bug in clang that will be fixed in the future, but in order
> to build cleanly with clang-8, it would be helpful to shut up this
> warning. This file is the only instance reported by kernelci at the
> moment.
> 
> The best solution I could come up with is to move the BIT() usage
> out of the macro into the instantiation, so we can avoid using
> BIT(-1).
> 
> Link: https://bugs.llvm.org/show_bug.cgi?id=38789
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Thanks, queued under arm/drivers now.


-Olof