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In-Reply-To: <20240315-mc-graph-fix-v1-1-91d59d752614@ideasonboard.com>
From: Naushir Patuck <naush@raspberrypi.com>
Date: Mon, 18 Mar 2024 08:41:23 +0000
Message-ID: <CAEmqJPoMmneTZAjJgOMRpd_B_236jh8NU8bpnaK6Odvnd1zcWg@mail.gmail.com>
Subject: Re: [PATCH] media: mc: Fix graph walk in media_pipeline_start
To: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>, 
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>, 
	Mauro Carvalho Chehab <mchehab@kernel.org>, linux-media@vger.kernel.org, 
	linux-kernel@vger.kernel.org
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Hi Tomi,

Thank you for this fix.

On Fri, 15 Mar 2024 at 15:13, Tomi Valkeinen
<tomi.valkeinen@ideasonboard.com> wrote:
>
> The graph walk tries to follow all links, even if they are not between
> pads. This causes a crash with, e.g. a MEDIA_LNK_FL_ANCILLARY_LINK link.
>
> Fix this by allowing the walk to proceed only for MEDIA_LNK_FL_DATA_LINK
> links.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Fixes: ae219872834a ("media: mc: entity: Rewrite media_pipeline_start()")

I was having problems with the Raspberry Pi Camera v3 module (IMX708 +
DW9817 VCM) that would crash in media_pipeline_start().  This patch
fixes the issue for me, so

Tested-by: Naushir Patuck <naush@raspberrypi.com>

> ---
>  drivers/media/mc/mc-entity.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
> index 543a392f8635..fcafe5c59052 100644
> --- a/drivers/media/mc/mc-entity.c
> +++ b/drivers/media/mc/mc-entity.c
> @@ -627,6 +627,12 @@ static int media_pipeline_explore_next_link(struct media_pipeline *pipe,
>                 return 0;
>         }
>
> +       if ((link->flags & MEDIA_LNK_FL_LINK_TYPE) != MEDIA_LNK_FL_DATA_LINK) {
> +               dev_dbg(walk->mdev->dev,
> +                       "media pipeline: skipping link (not data-link)\n");
> +               return 0;
> +       }
> +
>         /* Get the local pad and remote pad. */
>         if (link->source->entity == pad->entity) {
>                 local = link->source;
>
> ---
> base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
> change-id: 20240315-mc-graph-fix-8a2a245d7346
>
> Best regards,
> --
> Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>
>