[PATCH v2 0/2] Collapse vimc into single monolithic driver

Shuah Khan
2019-08-15T19:42:29Z

vimc uses Component API to split the driver into functional components.
The real hardware resembles a monolith structure than component and
component structure added a level of complexity making it hard to
maintain without adding any real benefit.

The sensor is one vimc component that would makes sense to be a separate
module to closely align with the real hardware. It would be easier to
collapse vimc into single monolithic driver first and then split the
sensor off as a separate module.

This patch series removes the component API and makes minimal changes to
the code base preserving the functional division of the code structure.
Preserving the functional structure allows us to split the sensor off
as a separate module in the future.

Major design elements in this change are:
- Use existing struct vimc_ent_config and struct vimc_pipeline_config
to drive the initialization of the functional components.
- Make vimc_device and vimc_ent_config global by moving them to
vimc-common.h
- Add two new hooks add and rm to initialize and register, unregister
and free subdevs.
- All component API is now gone and bind and unbind hooks are modified
to do "add" and "rm" with minimal changes to just add and rm subdevs.
- vimc-core's bind and unbind are now register and unregister.
- vimc-core invokes "add" hooks from its vimc_register_devices().
The "add" hooks remain the same and register subdevs. They don't
create platform devices of their own and use vimc's pdev.dev as
their reference device. The "add" hooks save their vimc_ent_device(s)
in the corresponding vimc_ent_config.
- vimc-core invokes "rm" hooks from its unregister to unregister
subdevs and cleanup.
- vimc-core invokes "add" and "rm" hooks with pointer to struct
vimc_device and the corresponding struct vimc_ent_config pointer.

The following configure and stream test works on all devices.

media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
media-ctl -d platform:vimc -V '"Sensor B":0[fmt:SBGGR8_1X8/640x480]'
media-ctl -d platform:vimc -V '"Debayer B":0[fmt:SBGGR8_1X8/640x480]'

v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440
v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
v4l2-ctl -z platform:vimc -d "Raw Capture 1" -v pixelformat=BA81

v4l2-ctl --stream-mmap --stream-count=100 -d /dev/video1
v4l2-ctl --stream-mmap --stream-count=100 -d /dev/video2
v4l2-ctl --stream-mmap --stream-count=100 -d /dev/video3

The second patch in the series fixes a general protection fault found
when rmmod is done while stream is active.

- rmmod while streaming returns vimc is in use
- rmmod without active stream works correctly

Changes since v1:
Patch 1 & 2: (patch 1 in this series)
- Collapsed the two patches into one
- Added common defines (vimc_device and vimc_ent_config) to vimc-common.h
based on our discussion.
- Addressed review comments from Helen and Laurent
- Use vimc-common.h instead of creating a new file.
- Other minor comments from Helen on int vs. unsigned int and
not needing to initialize ret in vimc_add_subdevs()
Patch 3 (patch 2 in this series):
- The second patch is the fix for gpf. Updated the patch after looking
at the test results from Andre and Helen. This problem is in a common
code and impacts all subdevs. The fix addresses the core problem and
fixes it. Fix removes pads release from v4l2_device_unregister_subdev()
and pads are now released from the sd release handler with all other
resources.

Outstanding:
- Update documentation with the correct topology.
- There is one outstanding gpf remaining in the unbind path. I will
fix that in a separate patch. This is an existing problem and will
be easier to fix on top of this patch series.

vimc_print_dot (--print-dot) topology after this change: (no change
compared to media master)
digraph board {
rankdir=TB
n00000001 [label="{{} | Sensor A\n/dev/v4l-subdev0 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
n00000001:port0 -> n00000005:port0 [style=bold]
n00000001:port0 -> n0000000b [style=bold]
n00000003 [label="{{} | Sensor B\n/dev/v4l-subdev1 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
n00000003:port0 -> n00000008:port0 [style=bold]
n00000003:port0 -> n0000000f [style=bold]
n00000005 [label="{{<port0> 0} | Debayer A\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
n00000005:port1 -> n00000015:port0
n00000008 [label="{{<port0> 0} | Debayer B\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
n00000008:port1 -> n00000015:port0 [style=dashed]
n0000000b [label="Raw Capture 0\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
n0000000f [label="Raw Capture 1\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
n00000013 [label="{{} | RGB/YUV Input\n/dev/v4l-subdev4 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
n00000013:port0 -> n00000015:port0 [style=dashed]
n00000015 [label="{{<port0> 0} | Scaler\n/dev/v4l-subdev5 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
n00000015:port1 -> n00000018 [style=bold]
n00000018 [label="RGB/YUV Capture\n/dev/video3", shape=box, style=filled, fillcolor=yellow]

Shuah Khan (2):
media: vimc: Collapse component structure into a single monolithic
driver
media: vimc: Fix gpf in rmmod path when stream is active

drivers/media/platform/vimc/Makefile | 7 +-
drivers/media/platform/vimc/vimc-capture.c | 75 ++-------
drivers/media/platform/vimc/vimc-common.c | 3 +-
drivers/media/platform/vimc/vimc-common.h | 54 ++++++
drivers/media/platform/vimc/vimc-core.c | 182 +++++++--------------
drivers/media/platform/vimc/vimc-debayer.c | 69 ++------
drivers/media/platform/vimc/vimc-scaler.c | 69 ++------
drivers/media/platform/vimc/vimc-sensor.c | 70 ++------
8 files changed, 161 insertions(+), 368 deletions(-)

--
2.17.1