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Subject: Re: [PATCH] drm/bridge: sil_sii8620: initialize return of
 sii8620_readb
To:     trix@redhat.com, narmstrong@baylibre.com,
        Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se,
        jernej.skrabec@siol.net, airlied@linux.ie, daniel@ffwll.ch,
        architt@codeaurora.org
Cc:     stable@vger.kernel.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org
From:   Andrzej Hajda <a.hajda@samsung.com>
Message-ID: <c79fd5b6-e999-5bec-e373-7709d07f4446@samsung.com>
Date:   Mon, 13 Jul 2020 17:29:37 +0200
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On 12.07.2020 17:24, trix@redhat.com wrote:
> From: Tom Rix <trix@redhat.com>
>
> clang static analysis flags this error
>
> sil-sii8620.c:184:2: warning: Undefined or garbage value
>    returned to caller [core.uninitialized.UndefReturn]
>          return ret;
>          ^~~~~~~~~~
>
> sii8620_readb calls sii8620_read_buf.
> sii8620_read_buf can return without setting its output
> pararmeter 'ret'.
>
> So initialize ret.
>
> Fixes: ce6e153f414a ("drm/bridge: add Silicon Image SiI8620 driver")
>
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
>   drivers/gpu/drm/bridge/sil-sii8620.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c b/drivers/gpu/drm/bridge/sil-sii8620.c
> index 3540e4931383..da933d477e5f 100644
> --- a/drivers/gpu/drm/bridge/sil-sii8620.c
> +++ b/drivers/gpu/drm/bridge/sil-sii8620.c
> @@ -178,7 +178,7 @@ static void sii8620_read_buf(struct sii8620 *ctx, u16 addr, u8 *buf, int len)
>   
>   static u8 sii8620_readb(struct sii8620 *ctx, u16 addr)
>   {
> -	u8 ret;
> +	u8 ret = 0;


In theory it shouldn't cause any harm, but this protections makes things 
simpler.

Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>

Regards
Andrzej


>   
>   	sii8620_read_buf(ctx, addr, &ret, 1);
>   	return ret;