linux-kernel - Re: [PATCH v3 2/2] media: cedrus: Add H264 decoding support

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Date:   Tue, 12 Feb 2019 13:47:13 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Ezequiel Garcia <ezequiel@...labora.com>
Cc:     hans.verkuil@...co.com, acourbot@...omium.org,
        sakari.ailus@...ux.intel.com,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        tfiga@...omium.org, posciak@...omium.org,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        nicolas.dufresne@...labora.com, jenskuske@...il.com,
        jernej.skrabec@...il.com, jonas@...boo.se,
        linux-sunxi@...glegroups.com,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v3 2/2] media: cedrus: Add H264 decoding support

On Mon, Feb 11, 2019 at 04:48:17PM -0300, Ezequiel Garcia wrote:
> On Mon, 2019-02-11 at 15:39 +0100, Maxime Ripard wrote:
> > Introduce some basic H264 decoding support in cedrus. So far, only the
> > baseline profile videos have been tested, and some more advanced features
> > used in higher profiles are not even implemented.
> > 
> > Signed-off-by: Maxime Ripard <maxime.ripard@...tlin.com>
> [..]
> 
> 
> > +static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
> > +				   struct cedrus_run *run,
> > +				   const u8 *ref_list, u8 num_ref,
> > +				   enum cedrus_h264_sram_off sram)
> > +{
> > +	const struct v4l2_ctrl_h264_decode_param *decode = run->h264.decode_param;
> > +	struct vb2_queue *cap_q = &ctx->fh.m2m_ctx->cap_q_ctx.q;
> > +	const struct vb2_buffer *dst_buf = &run->dst->vb2_buf;
> > +	struct cedrus_dev *dev = ctx->dev;
> > +	u8 sram_array[CEDRUS_MAX_REF_IDX];
> > +	unsigned int size, i;
> > +
> > +	memset(sram_array, 0, sizeof(sram_array));
> > +
> > +	for (i = 0; i < num_ref; i++) {
> > +		const struct v4l2_h264_dpb_entry *dpb;
> > +		const struct cedrus_buffer *cedrus_buf;
> > +		const struct vb2_v4l2_buffer *ref_buf;
> > +		unsigned int position;
> > +		int buf_idx;
> > +		u8 dpb_idx;
> > +
> > +		dpb_idx = ref_list[i];
> > +		dpb = &decode->dpb[dpb_idx];
> > +
> > +		if (!(dpb->flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
> > +			continue;
> > +
> > +		if (dst_buf->timestamp == dpb->timestamp)
> > +			buf_idx = dst_buf->index;
> > +		else
> > +			buf_idx = vb2_find_timestamp(cap_q, dpb->timestamp, 0);
> > +
> > +		if (buf_idx < 0)
> > +			continue;
> > +
> > +		ref_buf = to_vb2_v4l2_buffer(ctx->dst_bufs[buf_idx]);
> > +		cedrus_buf = vb2_v4l2_to_cedrus_buffer(ref_buf);
> > +		position = cedrus_buf->codec.h264.position;
> > +
> > +		sram_array[i] |= position << 1;
> > +		if (ref_buf->field == V4L2_FIELD_BOTTOM)
> > +			sram_array[i] |= BIT(0);
> > +	}
> > +
> > +	size = min((unsigned int)ALIGN(num_ref, 4), sizeof(sram_array));
> 
> Perhaps s/unsigned int/size_t, so the arguments to min() have the same type?
> 
> Otherwise, I got this warning:
> 
> /home/zeta/repos/linux/media_tree/drivers/staging/media/sunxi/cedrus/cedrus_h264.c: In function ‘_cedrus_write_ref_list’:
> /home/zeta/repos/linux/media_tree/include/linux/kernel.h:846:29: warning: comparison of distinct pointer types lacks a cast
>    (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))

Strange, I didn't notice any warning. I'll make sure to fix it.

Thanks!
Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com