Re: [PATCH v7 14/17] media: rkvdec: Add H264 support for the VDPU381 variant

From: Jianfeng Liu <liujianfeng1994@gmail.com>
To: detlev.casanova@collabora.com
Cc: corbet@lwn.net, daniel.almeida@collabora.com,
	didi.debian@cknow.org, ezequiel@vanguardiasur.com.ar,
	hansg@kernel.org, heiko@sntech.de, hverkuil@kernel.org,
	james.cowgill@blaize.com, jonas@kwiboo.se, kernel@collabora.com,
	laurent.pinchart@ideasonboard.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
	linux-rockchip@lists.infradead.org, mchehab@kernel.org,
	nicolas.dufresne@collabora.com, opensource206@gmail.com,
	ribalda@chromium.org, sakari.ailus@linux.intel.com,
	yunkec@google.com
Subject: Re: [PATCH v7 14/17] media: rkvdec: Add H264 support for the VDPU381 variant
Date: Sun, 21 Dec 2025 00:46:04 +0800	[thread overview]
Message-ID: <20251220164604.10052-1-liujianfeng1994@gmail.com> (raw)
In-Reply-To: <20251218232829.337811-15-detlev.casanova@collabora.com>

Hi,

On Thu, 18 Dec 2025 18:28:24 -0500, Detlev Casanova wrote:
>+static int rkvdec_h264_start(struct rkvdec_ctx *ctx)
>+{
>+	struct rkvdec_dev *rkvdec = ctx->dev;
>+	struct rkvdec_h264_priv_tbl *priv_tbl;
>+	struct rkvdec_h264_ctx *h264_ctx;
>+	struct v4l2_ctrl *ctrl;
>+	int ret;
>+
>+	ctrl = v4l2_ctrl_find(&ctx->ctrl_hdl,
>+			      V4L2_CID_STATELESS_H264_SPS);
>+	if (!ctrl)
>+		return -EINVAL;
>+
>+	h264_ctx = kzalloc(sizeof(*h264_ctx), GFP_KERNEL);
>+	if (!h264_ctx)
>+		return -ENOMEM;

I can see the sps validation is removed:

	ret = rkvdec_h264_validate_sps(ctx, ctrl->p_new.p_h264_sps);
	if (ret)
		return ret;

This should fix decoding issue with chromium when minimum size of h264
decoder is lower than 32. While I find this issue is caused by chromium
not following v4l2 stateless spec, and I think checking sps at start
should be still necessary.

I have sent a fix to chromium[1] and it should get merged later.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/7274555

Best regards,
Jianfeng