linux-kernel - Re: [PATCH] drm/bridge: anx7625: check the return on anx7625_aux

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Date:   Tue, 8 Mar 2022 14:57:07 -0800
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     trix@...hat.com
Cc:     andrzej.hajda@...el.com, narmstrong@...libre.com,
        robert.foss@...aro.org, laurent.pinchart@...asonboard.com,
        jonas@...boo.se, jernej.skrabec@...il.com, airlied@...ux.ie,
        daniel@...ll.ch, nathan@...nel.org, xji@...logixsemi.com,
        sam@...nborg.org, tzungbi@...gle.com, pihsun@...omium.org,
        maxime@...no.tech, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        hsinyi@...omium.org
Subject: Re: [PATCH] drm/bridge: anx7625: check the return on anx7625_aux_trans

On Thu, Mar 3, 2022 at 12:19 PM <trix@...hat.com> wrote:
>
> From: Tom Rix <trix@...hat.com>
>
> Clang static analysis reports this issue
> anx7625.c:876:13: warning: The left operand of '&' is
>   a garbage value
>   if (!(bcap & 0xOA01)) {
>         ~~~~ ^
>
> bcap is only set by a successful call to
> anx7625_aux_trans().  So check.
>
> Fixes: cd1637c7e480 ("drm/bridge: anx7625: add HDCP support")

Is this the correct Fixes tag?

I think it should be

Fixes: adca62ec370c ("drm/bridge: anx7625: Support reading edid
through aux channel")

instead.

> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  drivers/gpu/drm/bridge/analogix/anx7625.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index 633618bafd75d..f02ac079ed2ec 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -872,7 +872,10 @@ static int anx7625_hdcp_enable(struct anx7625_data *ctx)
>         }
>
>         /* Read downstream capability */
> -       anx7625_aux_trans(ctx, DP_AUX_NATIVE_READ, 0x68028, 1, &bcap);
> +       ret = anx7625_aux_trans(ctx, DP_AUX_NATIVE_READ, 0x68028, 1, &bcap);
> +       if (ret < 0)
> +               return ret;
> +
>         if (!(bcap & 0x01)) {
>                 pr_warn("downstream not support HDCP 1.4, cap(%x).\n", bcap);
>                 return 0;
> --
> 2.26.3
>


-- 
Thanks,
~Nick Desaulniers