linux-kernel - Re: [PATCH] drm/komeda: Use memset to initialize config

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Message-ID: <CAKwvOdk1DHiUkpByC-yReoO7udE-ipW_9D+EvHGSH8BiokcOMQ@mail.gmail.com>
Date:   Thu, 25 Apr 2019 10:25:20 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     "James (Qian) Wang" <james.qian.wang@....com>,
        Liviu Dudau <liviu.dudau@....com>,
        Brian Starkey <brian.starkey@....com>, malidp@...s.arm.com,
        dri-devel@...ts.freedesktop.org,
        LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] drm/komeda: Use memset to initialize config_id

On Wed, Apr 24, 2019 at 11:27 PM Nathan Chancellor
<natechancellor@...il.com> wrote:
>
> Clang warns:
>
> drivers/gpu/drm/arm/display/komeda/komeda_dev.c:76:38: warning: suggest
> braces around initialization of subobject [-Wmissing-braces]
>         union komeda_config_id config_id = {0,};
>                                             ^
>                                             {}
> 1 warning generated.
>
> One way to fix these warnings is to add additional braces like Clang
> suggests; however, there has been a bit of push back from some
> maintainers, who just prefer memset as it is unambiguous, doesn't
> depend on a particular compiler version, and properly initializes all
> subobjects [1][2]. Do that here so there are no more warnings.
>
> [1]: https://lore.kernel.org/lkml/022e41c0-8465-dc7a-a45c-64187ecd9684@amd.com/
> [2]: https://lore.kernel.org/lkml/20181128.215241.702406654469517539.davem@davemloft.net/
>
> Fixes: 4cc734cb79a8 ("drm/komeda: Add sysfs attribute: core_id and config_id")
> Link: https://github.com/ClangBuiltLinux/linux/issues/457
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
>  drivers/gpu/drm/arm/display/komeda/komeda_dev.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_dev.c b/drivers/gpu/drm/arm/display/komeda/komeda_dev.c
> index 9d6c31cca875..e605a518f59a 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_dev.c
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_dev.c
> @@ -73,9 +73,10 @@ config_id_show(struct device *dev, struct device_attribute *attr, char *buf)
>  {
>         struct komeda_dev *mdev = dev_to_mdev(dev);
>         struct komeda_pipeline *pipe = mdev->pipelines[0];
> -       union komeda_config_id config_id = {0,};

Haven't seen a trailing comma too often.  Thanks for the patch.
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

> +       union komeda_config_id config_id;
>         int i;
>
> +       memset(&config_id, 0, sizeof(config_id));
>         config_id.max_line_sz = pipe->layers[0]->hsize_in.end;
>         config_id.n_pipelines = mdev->n_pipelines;
>         config_id.n_scalers = pipe->n_scalers;
> --
> 2.21.0
>


-- 
Thanks,
~Nick Desaulniers