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Message-ID: <4b30c0bf-e525-1868-f625-569d4a104aa0@xs4all.nl>
Date: Fri, 7 Sep 2018 15:13:19 +0200
From: Hans Verkuil <hverkuil@...all.nl>
To: Paul Kocialkowski <contact@...lk.fr>, linux-media@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, devel@...verdev.osuosl.org
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Maxime Ripard <maxime.ripard@...tlin.com>,
Chen-Yu Tsai <wens@...e.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
linux-sunxi@...glegroups.com, Randy Li <ayaka@...lik.info>,
Ezequiel Garcia <ezequiel@...labora.com>,
Tomasz Figa <tfiga@...omium.org>,
Alexandre Courbot <acourbot@...omium.org>,
Philipp Zabel <p.zabel@...gutronix.de>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Sakari Ailus <sakari.ailus@...ux.intel.com>
Subject: Re: [PATCH v9 5/9] media: platform: Add Cedrus VPU decoder driver
On 09/07/2018 12:24 AM, Paul Kocialkowski wrote:
> From: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
>
> This introduces the Cedrus VPU driver that supports the VPU found in
> Allwinner SoCs, also known as Video Engine. It is implemented through
> a V4L2 M2M decoder device and a media device (used for media requests).
> So far, it only supports MPEG-2 decoding.
>
> Since this VPU is stateless, synchronization with media requests is
> required in order to ensure consistency between frame headers that
> contain metadata about the frame to process and the raw slice data that
> is used to generate the frame.
>
> This driver was made possible thanks to the long-standing effort
> carried out by the linux-sunxi community in the interest of reverse
> engineering, documenting and implementing support for the Allwinner VPU.
>
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> Acked-by: Maxime Ripard <maxime.ripard@...tlin.com>
One high-level comment:
Can you add a TODO file for this staging driver? This can be done in
a follow-up patch.
It should contain what needs to be done to get this out of staging:
- Request API needs to stabilize
- Userspace support for stateless codecs must be created
- Ideally one other stateless decoder driver and at least one
stateless encoder driver should be implemented to ensure that nothing
was forgotten in the Request API.
- Anything else?
And a few last code comments:
> ---
> MAINTAINERS | 7 +
> drivers/staging/media/Kconfig | 2 +
> drivers/staging/media/Makefile | 1 +
> drivers/staging/media/sunxi/Kconfig | 15 +
> drivers/staging/media/sunxi/Makefile | 1 +
> drivers/staging/media/sunxi/cedrus/Kconfig | 14 +
> drivers/staging/media/sunxi/cedrus/Makefile | 3 +
> drivers/staging/media/sunxi/cedrus/cedrus.c | 422 ++++++++++++++
> drivers/staging/media/sunxi/cedrus/cedrus.h | 165 ++++++
> .../staging/media/sunxi/cedrus/cedrus_dec.c | 70 +++
> .../staging/media/sunxi/cedrus/cedrus_dec.h | 27 +
> .../staging/media/sunxi/cedrus/cedrus_hw.c | 322 +++++++++++
> .../staging/media/sunxi/cedrus/cedrus_hw.h | 30 +
> .../staging/media/sunxi/cedrus/cedrus_mpeg2.c | 237 ++++++++
> .../staging/media/sunxi/cedrus/cedrus_regs.h | 233 ++++++++
> .../staging/media/sunxi/cedrus/cedrus_video.c | 544 ++++++++++++++++++
> .../staging/media/sunxi/cedrus/cedrus_video.h | 30 +
> 17 files changed, 2123 insertions(+)
> create mode 100644 drivers/staging/media/sunxi/Kconfig
> create mode 100644 drivers/staging/media/sunxi/Makefile
> create mode 100644 drivers/staging/media/sunxi/cedrus/Kconfig
> create mode 100644 drivers/staging/media/sunxi/cedrus/Makefile
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus.c
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus.h
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_dec.h
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_hw.c
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_hw.h
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_regs.h
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_video.c
> create mode 100644 drivers/staging/media/sunxi/cedrus/cedrus_video.h
>
<snip>
> +static int cedrus_request_validate(struct media_request *req)
> +{
> + struct media_request_object *obj;
> + struct v4l2_ctrl_handler *parent_hdl, *hdl;
> + struct cedrus_ctx *ctx = NULL;
> + struct v4l2_ctrl *ctrl_test;
> + unsigned int i;
> +
> + if (vb2_request_buffer_cnt(req) != 1)
> + return -ENOENT;
I would return ENOENT if there are no buffers, and EINVAL if there are too
many. Returning ENOENT in the latter case would be very confusing.
I also highly recommend that you add v4l2_info lines for these errors.
> +
> + list_for_each_entry(obj, &req->objects, list) {
> + struct vb2_buffer *vb;
> +
> + if (vb2_request_object_is_buffer(obj)) {
> + vb = container_of(obj, struct vb2_buffer, req_obj);
> + ctx = vb2_get_drv_priv(vb->vb2_queue);
> +
> + break;
> + }
> + }
> +
> + if (!ctx)
> + return -ENOENT;
> +
> + parent_hdl = &ctx->hdl;
> +
> + hdl = v4l2_ctrl_request_hdl_find(req, parent_hdl);
> + if (!hdl) {
> + v4l2_err(&ctx->dev->v4l2_dev, "Missing codec control(s)\n");
Should be v4l2_info: it is not a driver error, it is just an info message.
> + return -ENOENT;
> + }
> +
> + for (i = 0; i < CEDRUS_CONTROLS_COUNT; i++) {
> + if (cedrus_controls[i].codec != ctx->current_codec ||
> + !cedrus_controls[i].required)
> + continue;
> +
> + ctrl_test = v4l2_ctrl_request_hdl_ctrl_find(hdl,
> + cedrus_controls[i].id);
> + if (!ctrl_test) {
> + v4l2_err(&ctx->dev->v4l2_dev,
> + "Missing required codec control\n");
Ditto.
> + return -ENOENT;
> + }
> + }
> +
> + v4l2_ctrl_request_hdl_put(hdl);
> +
> + return vb2_request_validate(req);
> +}
Not worth making a v10, but you can do this in a follow-up patch.
Once I have the two follow-up patches I'll make a pull request.
Regards,
Hans
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