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Message-ID: <c5e826a2-5bc6-4c49-9a6d-655d26a3b97f@xs4all.nl>
Date:   Mon, 16 Oct 2023 13:57:37 +0200
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Subject: Re: [PATCH v13 5/8] media: chips-media: wave5: Add the v4l2 layer
Content-Language: en-US, nl
To:     Sebastian Fricke <sebastian.fricke@collabora.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        NXP Linux Team <linux-imx@nxp.com>,
        Conor Dooley <conor+dt@kernel.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Jackson Lee <jackson.lee@chipsnmedia.com>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Rob Herring <robh+dt@kernel.org>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Nas Chung <nas.chung@chipsnmedia.com>,
        Fabio Estevam <festevam@gmail.com>
Cc:     linux-media@vger.kernel.org, Tomasz Figa <tfiga@chromium.org>,
        linux-kernel@vger.kernel.org,
        Nicolas Dufresne <nicolas.dufresne@collabora.com>,
        kernel@collabora.com, Robert Beckett <bob.beckett@collabora.com>,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Darren Etheridge <detheridge@ti.com>
References: <20230929-wave5_v13_media_master-v13-0-5ac60ccbf2ce@collabora.com>
 <20230929-wave5_v13_media_master-v13-5-5ac60ccbf2ce@collabora.com>
From:   Hans Verkuil <hverkuil@xs4all.nl>
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In-Reply-To: <20230929-wave5_v13_media_master-v13-5-5ac60ccbf2ce@collabora.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi Sebastian,

On 12/10/2023 13:01, Sebastian Fricke wrote:
> Add the decoder and encoder implementing the v4l2
> API. This patch also adds the Makefile and the VIDEO_WAVE_VPU config
> 
> Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>
> Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
> Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
> Signed-off-by: Robert Beckett <bob.beckett@collabora.com>
> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
> Signed-off-by: Nas Chung <nas.chung@chipsnmedia.com>
> ---
>  drivers/media/platform/chips-media/Kconfig         |    1 +
>  drivers/media/platform/chips-media/Makefile        |    1 +
>  drivers/media/platform/chips-media/wave5/Kconfig   |   12 +
>  drivers/media/platform/chips-media/wave5/Makefile  |   10 +
>  .../platform/chips-media/wave5/wave5-helper.c      |  213 +++
>  .../platform/chips-media/wave5/wave5-helper.h      |   31 +
>  .../platform/chips-media/wave5/wave5-vpu-dec.c     | 1953 ++++++++++++++++++++
>  .../platform/chips-media/wave5/wave5-vpu-enc.c     | 1794 ++++++++++++++++++
>  .../media/platform/chips-media/wave5/wave5-vpu.c   |  291 +++
>  .../media/platform/chips-media/wave5/wave5-vpu.h   |   83 +
>  .../platform/chips-media/wave5/wave5-vpuapi.h      |    2 -
>  11 files changed, 4389 insertions(+), 2 deletions(-)
> 

<snip>

> +static int wave5_vpu_dec_create_bufs(struct file *file, void *priv,
> +				     struct v4l2_create_buffers *create)
> +{
> +	struct vpu_instance *inst = wave5_to_vpu_inst(priv);
> +	struct v4l2_format *f = &create->format;
> +
> +	/* Firmware does not support CREATE_BUFS for CAPTURE queues. */
> +	if (f->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) {
> +		dev_dbg(inst->dev->dev,
> +			"%s: VIDIOC_CREATE_BUFS not supported on CAPTURE queues.\n",
> +			__func__);
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return v4l2_m2m_ioctl_create_bufs(file, priv, create);
> +}

Regarding the EOPNOTSUPP discussion: I discussed this some more with
Nicolas on irc, and we wonder if it isn't better to just drop create_bufs
support for the wave5 decoder altogether. Is there any point in supporting
it for OUTPUT but not CAPTURE?

<snip>

> +static const struct v4l2_ioctl_ops wave5_vpu_dec_ioctl_ops = {
> +	.vidioc_querycap = wave5_vpu_dec_querycap,
> +	.vidioc_enum_framesizes = wave5_vpu_dec_enum_framesizes,
> +
> +	.vidioc_enum_fmt_vid_cap	= wave5_vpu_dec_enum_fmt_cap,
> +	.vidioc_s_fmt_vid_cap_mplane = wave5_vpu_dec_s_fmt_cap,
> +	.vidioc_g_fmt_vid_cap_mplane = wave5_vpu_dec_g_fmt_cap,
> +	.vidioc_try_fmt_vid_cap_mplane = wave5_vpu_dec_try_fmt_cap,
> +
> +	.vidioc_enum_fmt_vid_out	= wave5_vpu_dec_enum_fmt_out,
> +	.vidioc_s_fmt_vid_out_mplane = wave5_vpu_dec_s_fmt_out,
> +	.vidioc_g_fmt_vid_out_mplane = wave5_vpu_g_fmt_out,
> +	.vidioc_try_fmt_vid_out_mplane = wave5_vpu_dec_try_fmt_out,
> +
> +	.vidioc_g_selection = wave5_vpu_dec_g_selection,
> +	.vidioc_s_selection = wave5_vpu_dec_s_selection,
> +
> +	.vidioc_reqbufs = v4l2_m2m_ioctl_reqbufs,
> +	.vidioc_querybuf = v4l2_m2m_ioctl_querybuf,
> +	.vidioc_create_bufs = wave5_vpu_dec_create_bufs,

So this would just be dropped.

> +	.vidioc_prepare_buf = v4l2_m2m_ioctl_prepare_buf,
> +	.vidioc_qbuf = v4l2_m2m_ioctl_qbuf,
> +	.vidioc_expbuf = v4l2_m2m_ioctl_expbuf,
> +	.vidioc_dqbuf = v4l2_m2m_ioctl_dqbuf,
> +	.vidioc_streamon = v4l2_m2m_ioctl_streamon,
> +	.vidioc_streamoff = v4l2_m2m_ioctl_streamoff,
> +
> +	.vidioc_try_decoder_cmd = v4l2_m2m_ioctl_try_decoder_cmd,
> +	.vidioc_decoder_cmd = wave5_vpu_dec_decoder_cmd,
> +
> +	.vidioc_subscribe_event = wave5_vpu_subscribe_event,
> +	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
> +};

This also means there is no need to document the new EOPNOTSUPP error
code in VIDIOC_CREATE_BUFS, or to modify v4l2-compliance.

You *do* need to add a comment somewhere explaining why you don't
support this ioctl. I think it would be best to do that right after
'.vidioc_reqbufs = v4l2_m2m_ioctl_reqbufs,'.

Regards,

	Hans