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Subject: Re: [PATCH v5 0/2] media: platform: Add Aspeed Video Engine Driver
To: Eddie James <eajames@linux.ibm.com>, linux-kernel@vger.kernel.org
Cc: mchehab@kernel.org, linux-media@vger.kernel.org,
        robh+dt@kernel.org, andrew@aj.id.au, linux-aspeed@lists.ozlabs.org,
        devicetree@vger.kernel.org, mark.rutland@arm.com,
        Eddie James <eajames@linux.vnet.ibm.com>
References: <1542056431-18146-1-git-send-email-eajames@linux.ibm.com>
From: Hans Verkuil <hverkuil@xs4all.nl>
Message-ID: <9b21fb44-2248-7921-2205-4a3f43d22d4b@xs4all.nl>
Date: Thu, 15 Nov 2018 10:20:06 +0100
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On 11/12/2018 10:00 PM, Eddie James wrote:
> From: Eddie James <eajames@linux.vnet.ibm.com>
> 
> The Video Engine (VE) embedded in the Aspeed AST2400 and AST2500 SOCs
> can capture and compress video data from digital or analog sources. With
> the Aspeed chip acting as a service processor, the Video Engine can
> capture the host processor graphics output.
> 
> This series adds a V4L2 driver for the VE, providing the usual V4L2 streaming
> interface by way of videobuf2. Each frame, the driver triggers the hardware to
> capture the host graphics output and compress it to JPEG format.

I reviewed the driver, and there is still confusion about active timings and
detected timings. You are really close, but it is still not right.

The timings returned by G_DV_TIMINGS should never change, unless by calling
S_DV_TIMINGS. The format returned by G_FMT should never change, unless by
calling S_DV_TIMINGS (which implicitly changes the format) or S_FMT.

Timings changes from the video or calling QUERY_DV_TIMINGS should have NO
effect on the timings/format returned by G_DV_TIMINGS/G_FMT.

Obviously, if the video timings change, then streaming will halt and an event
is issued so userspace can take action.

> 
> v4l-utils HEAD dd3ff81f58c4e1e6f33765dc61ad33c48ae6bb07
> 
> v4l2-compliance SHA: not available, 32 bits

<snip>

> Control ioctls (Input 0):
> 	test VIDIOC_QUERY_EXT_CTRL/QUERYMENU: OK
> 	test VIDIOC_QUERYCTRL: OK
> 	test VIDIOC_G/S_CTRL: OK
> 	test VIDIOC_G/S/TRY_EXT_CTRLS: OK
> 		fail: v4l2-test-controls.cpp(823): failed to find event for control 'Chroma Subsampling'

That's weird. It's not clear to me why this fails.

> 	test VIDIOC_(UN)SUBSCRIBE_EVENT/DQEVENT: FAIL
> 	test VIDIOC_G/S_JPEGCOMP: OK (Not Supported)
> 	Standard Controls: 3 Private Controls: 0
> 
> Format ioctls (Input 0):
> 	test VIDIOC_ENUM_FMT/FRAMESIZES/FRAMEINTERVALS: OK
> 	test VIDIOC_G/S_PARM: OK
> 	test VIDIOC_G_FBUF: OK (Not Supported)
> 	test VIDIOC_G_FMT: OK
> 	test VIDIOC_TRY_FMT: OK
> 	test VIDIOC_S_FMT: OK
> 	test VIDIOC_G_SLICED_VBI_CAP: OK (Not Supported)
> 	test Cropping: OK (Not Supported)
> 	test Composing: OK (Not Supported)
> 	test Scaling: OK (Not Supported)
> 
> Codec ioctls (Input 0):
> 	test VIDIOC_(TRY_)ENCODER_CMD: OK (Not Supported)
> 	test VIDIOC_G_ENC_INDEX: OK (Not Supported)
> 	test VIDIOC_(TRY_)DECODER_CMD: OK (Not Supported)
> 
> Buffer ioctls (Input 0):
> 		fail: v4l2-test-buffers.cpp(422): dmabuf_valid ^ !!(caps & V4L2_BUF_CAP_SUPPORTS_DMABUF)

I updated v4l2-compliance, as this test was a bit too strict.

> 	test VIDIOC_REQBUFS/CREATE_BUFS/QUERYBUF: FAIL
> 	test VIDIOC_EXPBUF: OK (Not Supported)
> 
> Test input 0:
> 
> Streaming ioctls:
> 	test read/write: OK
> 	test blocking wait: OK
> 	test MMAP: OK                                     
> 	test USERPTR: OK (Not Supported)
> 		fail: v4l2-test-buffers.cpp(1102): exp_q.reqbufs(expbuf_node, q.g_buffers())
> 		fail: v4l2-test-buffers.cpp(1192): setupDmaBuf(expbuf_node, node, q, exp_q)

You need to add:

	.vidioc_expbuf = vb2_ioctl_expbuf,

to aspeed_video_ioctl_ops.

> 	test DMABUF: FAIL
> 
> Total: 48, Succeeded: 45, Failed: 3, Warnings: 0
> 
> The apparent rate of change to the v4l2/vb2 API makes it difficult to pass
> these tests. None of the failing tests even ran last time I submitted my
> series. And V4L2_BUF_CAP_SUPPORTS_DMABUF is undefined in 4.19.

When developing new drivers you should use the master branch of
https://git.linuxtv.org/media_tree.git/

The v4l-utils repo is kept in sync with the latest code from that master branch.

Regards,

	Hans

> 
> Changes since v4:
>  - Set real min and max resolution in enum_dv_timings
>  - Add check for vb2_is_busy before settings the timings
>  - Set max frame rate to the actual max rather than max + 1
>  - Correct the input status to 0.
>  - Rework resolution change to only set the relevant h/w regs during startup or
>    when set_timings is called.
> 
> Changes since v3:
>  - Switch update reg function to use u32 clear rather than unsigned long mask
>  - Add timing information from host VGA signal
>  - Fix binding documentation mispelling
>  - Fix upper case hex values
>  - Add wait_prepare and wait_finish
>  - Set buffer state to queued (rather than error) if streaming fails to start
>  - Switch engine busy print statement to error
>  - Removed a couple unecessary type assignments in v4l2 ioctls
>  - Added query_dv_timings, fixed get_dv_timings
>  - Corrected source change event to fire if and only if size actually changes
>  - Locked open and release
> 
> Changes since v2:
>  - Switch to streaming interface. This involved a lot of changes.
>  - Rework memory allocation due to using videobuf2 buffers, but also only
>    allocate the necessary size of source buffer rather than the max size
> 
> Changes since v1:
>  - Removed le32_to_cpu calls for JPEG header data
>  - Reworked v4l2 ioctls to be compliant.
>  - Added JPEG controls
>  - Updated devicetree docs according to Rob's suggestions.
>  - Added myself to MAINTAINERS
> 
> Eddie James (2):
>   dt-bindings: media: Add Aspeed Video Engine binding documentation
>   media: platform: Add Aspeed Video Engine driver
> 
>  .../devicetree/bindings/media/aspeed-video.txt     |   26 +
>  MAINTAINERS                                        |    8 +
>  drivers/media/platform/Kconfig                     |    9 +
>  drivers/media/platform/Makefile                    |    1 +
>  drivers/media/platform/aspeed-video.c              | 1711 ++++++++++++++++++++
>  5 files changed, 1755 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/aspeed-video.txt
>  create mode 100644 drivers/media/platform/aspeed-video.c
>