From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>,
linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rtc: ds2404: use hw endiannes variable
Date: Thu, 23 May 2019 17:42:44 +0200 [thread overview]
Message-ID: <20190523154244.GU3274@piout.net> (raw)
In-Reply-To: <1557368035-6787-1-git-send-email-hofrat@osadl.org>
On 09/05/2019 04:13:55+0200, Nicholas Mc Guire wrote:
> Converting from hardware to host endiannes was done using reassignment
> to the same variable which makes sparse unhappy as it can not verify
> the endiannes handling properly. To allow sparse to verify endiannes
> handling an explicit __le32 is introduced. Note that this patch does
> not change the generated binary (x86_64 and ppc64 binary diff).
>
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> ---
>
> Problem located by an experimental coccinelle script to locate
> patters that make sparse unhappy (false positives):
>
> on little-endian x86_64 sparse complains about:
> drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32
> on big-endian ppc64 sparse complains about
> drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32
> drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32
> drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32
> drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32
> drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32
> drivers/rtc/rtc-ds2404.c:187:16: warning: cast to restricted __le32
>
> Patch was compiletested with:
> x86_64_defconfig + RTC_DRV_DS2404=m
> ppc64_defconfig + RTC_DRV_DS2404=m
>
> in both cases applying the patch has no impact on the generated binary.
>
> Patch is against 5.1 (localversion-next is next-20190508)
>
> drivers/rtc/rtc-ds2404.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
Applied, thanks.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
prev parent reply other threads:[~2019-05-23 15:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-09 2:13 [PATCH] rtc: ds2404: use hw endiannes variable Nicholas Mc Guire
2019-05-23 15:42 ` Alexandre Belloni [this message]
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