On 04/30/2015 12:53 AM, Mikhail Ulyanov wrote:
Here's the the driver for the Renesas R-Car JPEG processing unit driver.
One "the" is enough. And one "driver" too, you probbaly forgot to remove
the word at the end.
The driver is implemented within the V4L2 framework as a mem-to-mem device. It
Perhaps "memory-to-memory"?
presents two video nodes to userspace, one for the encoding part, and one for
the decoding part.
It was found that the only working mode for encoding is no markers output, so we
generate it with software. In current version of driver we also use software
JPEG header parsing because with hardware parsing performance is lower then
desired.
From a userspace point of view the encoding process is typical (S_FMT, REQBUF,
optionally QUERYBUF, QBUF, STREAMON, DQBUF) for both the source and destination
queues. The decoding process requires that the source queue performs S_FMT,
REQBUF, (QUERYBUF), QBUF and STREAMON. After STREAMON on the source queue, it is
possible to perform G_FMT on the destination queue to find out the processed
image width and height in order to be able to allocate an appropriate buffer -
it is assumed that the user does not pass the compressed image width and height
but instead this information is parsed from the JPEG input. This is done in
kernel. Then REQBUF, QBUF and STREAMON on the destination queue complete the
decoding and it is possible to DQBUF from both queues and finish the operation.
During encoding the available formats are: V4L2_PIX_FMT_NV12M and
V4L2_PIX_FMT_NV16M for source and V4L2_PIX_FMT_JPEG for destination.
During decoding the available formats are: V4L2_PIX_FMT_JPEG for source and
V4L2_PIX_FMT_NV12M and V4L2_PIX_FMT_NV16M for destination.
Performance of current version:
1280x800 NV12 image encoding/decoding
decoding ~121 FPS
encoding ~190 FPS
Signed-off-by: Mikhail Ulyanov <mikhail.ulyanov@xxxxxxxxxxxxxxxxxx>
---
Changes since v2:
- Kconfig entry reordered
- unnecessary clk_disable_unprepare(jpu->clk) removed
- ref_count fixed in jpu_resume
- enable DMABUF in src_vq->io_modes
- remove jpu_s_priority jpu_g_priority
- jpu_g_selection fixed
- timeout in jpu_reset added and hardware reset reworked
- remove unused macros
- JPEG header parsing now is software because of performance issues
based on s5p-jpu code
- JPEG header generation redesigned:
JPEG header(s) pre-generated and memcpy'ed on encoding
we only fill the necessary fields
more "transparent" header format description
- S_FMT, G_FMT and TRY_FMT hooks redesigned
Still need a comma before "and" -- the English punctuation rules are
different from the Russian ones.
partially inspired by VSP1 driver code
- some code was reformatted
- image formats handling redesigned
- multi-planar V4L2 API now in use
- now passes v4l2-compliance tool check
Cnanges since v1:
- s/g_fmt function simplified
- default format for queues added
- dumb vidioc functions added to be in compliance with standard api:
jpu_s_priority, jpu_g_priority
- standard v4l2_ctrl_subscribe_event and v4l2_event_unsubscribe
now in use by the same reason
[...]
WBR, Sergei
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