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Subject: Re: [PATCH v6 3/4] media: meson: add v4l2 m2m video decoder driver
To:     Hans Verkuil <hverkuil@xs4all.nl>,
        Maxime Jourdan <mjourdan@baylibre.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>
Cc:     Hans Verkuil <hans.verkuil@cisco.com>,
        Kevin Hilman <khilman@baylibre.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org
References: <20190514135612.30822-1-mjourdan@baylibre.com>
 <20190514135612.30822-4-mjourdan@baylibre.com>
 <07af1a22-d57c-aff6-b476-98fbf72135c1@xs4all.nl>
From:   Neil Armstrong <narmstrong@baylibre.com>
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Organization: Baylibre
Message-ID: <480f2c43-9858-a4d3-7a6b-452756fb6076@baylibre.com>
Date:   Mon, 27 May 2019 12:18:53 +0200
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In-Reply-To: <07af1a22-d57c-aff6-b476-98fbf72135c1@xs4all.nl>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Hans,

On 27/05/2019 12:04, Hans Verkuil wrote:
> Hi Maxime,
> 
> First a high-level comment: I think this driver should go to staging.
> Once we finalize the stateful decoder spec, and we've updated the
> v4l2-compliance test, then this needs to be tested against that and
> only if it passes can it be moved out of staging.

I don't understand the reason since other stateful codecs are already
mainline and doesn't match the in-discussion stateful decoder spec either.

Neil

> 
> It is just a bit too soon to have this in mainline at this time.
> 
> One other comment below:
> 
> On 5/14/19 3:56 PM, Maxime Jourdan wrote:
>> Amlogic SoCs feature a powerful video decoder unit able to
>> decode many formats, with a performance of usually up to 4k60.
>>
>> This is a driver for this IP that is based around the v4l2 m2m framework.
>>
>> It features decoding for:
>> - MPEG 1
>> - MPEG 2
>>
>> Supported SoCs are: GXBB (S905), GXL (S905X/W/D), GXM (S912)
>>
>> There is also a hardware bitstream parser (ESPARSER) that is handled here.
>>
>> Tested-by: Neil Armstrong <narmstrong@baylibre.com>
>> Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
>> ---
>>  drivers/media/platform/Kconfig                |   10 +
>>  drivers/media/platform/meson/Makefile         |    1 +
>>  drivers/media/platform/meson/vdec/Makefile    |    8 +
>>  .../media/platform/meson/vdec/codec_mpeg12.c  |  209 ++++
>>  .../media/platform/meson/vdec/codec_mpeg12.h  |   14 +
>>  drivers/media/platform/meson/vdec/dos_regs.h  |   98 ++
>>  drivers/media/platform/meson/vdec/esparser.c  |  323 +++++
>>  drivers/media/platform/meson/vdec/esparser.h  |   32 +
>>  drivers/media/platform/meson/vdec/vdec.c      | 1071 +++++++++++++++++
>>  drivers/media/platform/meson/vdec/vdec.h      |  265 ++++
>>  drivers/media/platform/meson/vdec/vdec_1.c    |  229 ++++
>>  drivers/media/platform/meson/vdec/vdec_1.h    |   14 +
>>  .../media/platform/meson/vdec/vdec_ctrls.c    |   51 +
>>  .../media/platform/meson/vdec/vdec_ctrls.h    |   14 +
>>  .../media/platform/meson/vdec/vdec_helpers.c  |  441 +++++++
>>  .../media/platform/meson/vdec/vdec_helpers.h  |   80 ++
>>  .../media/platform/meson/vdec/vdec_platform.c |  107 ++
>>  .../media/platform/meson/vdec/vdec_platform.h |   30 +
>>  18 files changed, 2997 insertions(+)
>>  create mode 100644 drivers/media/platform/meson/vdec/Makefile
>>  create mode 100644 drivers/media/platform/meson/vdec/codec_mpeg12.c
>>  create mode 100644 drivers/media/platform/meson/vdec/codec_mpeg12.h
>>  create mode 100644 drivers/media/platform/meson/vdec/dos_regs.h
>>  create mode 100644 drivers/media/platform/meson/vdec/esparser.c
>>  create mode 100644 drivers/media/platform/meson/vdec/esparser.h
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec.c
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec.h
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec_1.c
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec_1.h
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec_ctrls.c
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec_ctrls.h
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec_helpers.c
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec_helpers.h
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec_platform.c
>>  create mode 100644 drivers/media/platform/meson/vdec/vdec_platform.h
>>
> 
> <snip>
> 
>> diff --git a/drivers/media/platform/meson/vdec/vdec_ctrls.c b/drivers/media/platform/meson/vdec/vdec_ctrls.c
>> new file mode 100644
>> index 000000000000..d5d6b1b97aa5
>> --- /dev/null
>> +++ b/drivers/media/platform/meson/vdec/vdec_ctrls.c
>> @@ -0,0 +1,51 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Copyright (C) 2018 BayLibre, SAS
>> + * Author: Maxime Jourdan <mjourdan@baylibre.com>
>> + */
>> +
>> +#include "vdec_ctrls.h"
>> +
>> +static int vdec_op_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
>> +{
>> +	struct amvdec_session *sess =
>> +	      container_of(ctrl->handler, struct amvdec_session, ctrl_handler);
>> +
>> +	switch (ctrl->id) {
>> +	case V4L2_CID_MIN_BUFFERS_FOR_CAPTURE:
>> +		ctrl->val = sess->dpb_size;
>> +		break;
>> +	default:
>> +		return -EINVAL;
>> +	};
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct v4l2_ctrl_ops vdec_ctrl_ops = {
>> +	.g_volatile_ctrl = vdec_op_g_volatile_ctrl,
>> +};
>> +
>> +int amvdec_init_ctrls(struct v4l2_ctrl_handler *ctrl_handler)
>> +{
>> +	int ret;
>> +	struct v4l2_ctrl *ctrl;
>> +
>> +	ret = v4l2_ctrl_handler_init(ctrl_handler, 1);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ctrl = v4l2_ctrl_new_std(ctrl_handler, &vdec_ctrl_ops,
>> +		V4L2_CID_MIN_BUFFERS_FOR_CAPTURE, 1, 32, 1, 1);
>> +	if (ctrl)
>> +		ctrl->flags |= V4L2_CTRL_FLAG_VOLATILE;
> 
> Why is this volatile? That makes little sense.
> 
>> +
>> +	ret = ctrl_handler->error;
>> +	if (ret) {
>> +		v4l2_ctrl_handler_free(ctrl_handler);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(amvdec_init_ctrls);
> 
> <snip>
> 
> Regards,
> 
> 	Hans
>