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

Shuah Khan
2019-08-19T18:00:31Z

On 8/16/19 2:03 PM, Helen Koike wrote:
> Hi Shuah,
>
> Thanks for the patches.
>
> On 8/15/19 4:42 PM, Shuah Khan wrote:
>> 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
>
> I couldn't apply those on top of media/master, I think they are
> conflicting with the two "Reverts" commits in vimc.
>

Sorry for the delay. I was out backpacking for a couple of days.

I knew I have to rebase after the reverts go in. I will do that
and address your comments on patch 1/2 and resend the series.

Thanks for the review. Your comments on naming make sense.

thanks,
-- Shuah