RE: [PATCH v6 0/2] Add support for Xilinx CSI2 Receiver Subsystem

[Vishal Sagar]

Hi Eugen,

Thanks for reaching out.

> -----Original Message-----
> From: Eugen.Hristev@xxxxxxxxxxxxx [mailto:Eugen.Hristev@xxxxxxxxxxxxx]
> Sent: Tuesday, March 12, 2019 4:30 PM
> To: vishal.sagar@xxxxxxxxxx; Hyun Kwon <hyunk@xxxxxxxxxx>;
> laurent.pinchart@xxxxxxxxxxxxxxxx; mchehab@xxxxxxxxxx;
> robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx; Michal Simek
> <michals@xxxxxxxxxx>; linux-media@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; sakari.ailus@xxxxxxxxxxxxxxx;
> hans.verkuil@xxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Dinesh Kumar <dineshk@xxxxxxxxxx>; Sandip Kothari
> <sandipk@xxxxxxxxxx>
> Subject: Re: [PATCH v6 0/2] Add support for Xilinx CSI2 Receiver Subsystem
> 
> EXTERNAL EMAIL
> 
> On 12.03.2019 06:35, Vishal Sagar wrote:
> > Xilinx MIPI CSI-2 Receiver Subsystem
> > ------------------------------------
> >
> > The Xilinx MIPI CSI-2 Receiver Subsystem Soft IP consists of a DPHY which
> > gets the data, an optional I2C, a CSI-2 Receiver which parses the data and
> > converts it into AXIS data.
> > This stream output maybe connected to a Xilinx Video Format Bridge.
> > The maximum number of lanes supported is fixed in the design.
> > The number of active lanes can be programmed.
> > For e.g. the design may set maximum lanes as 4 but if the camera sensor has
> > only 1 lane then the active lanes shall be set as 1.
> >
> > The pixel format set in design acts as a filter allowing only the selected
> > data type or RAW8 data packets. The D-PHY register access can be gated in
> > the design. The base address of the DPHY depends on whether the internal
> > Xilinx I2C controller is enabled or not in design.
> 
> Hi Vishal,
> 
> Do you also include a driver for the DPHY ? Namely I am interested in
> something which can comply to the PHY subsystem specifications, so it
> can be referenced by possibly other nodes ?
>

No the DPHY driver isn't included now as the DPHY register interface can be optionally enabled.
But the idea is to add that kind of support in future.

> Something like this:
> 
> xilinx_dphy: dphy@40000 {
>                          compatible = "xlnx,dphy";
> 
>                          #phy-cells = <0>;
> 
>                          reg = <0x40000 0x100>;
> 
>                  };
> 
>  From my understanding your RX system can be referenced as a whole,
> without being able to have the PHY as separate node, and creating
> references maybe like :
> 
> phys = <&xilinx_dphy>;
> 

True. Currently this is how it is implemented without the phys dt entry.

Regards
Vishal Sagar

> 
> Thanks,
> 
> Eugen
> 
> 
> 
> >
> > The device driver registers the MIPI CSI2 Rx Subsystem as a V4L2 sub device
> > having 2 pads. The sink pad is connected to the MIPI camera sensor and
> > output pad is connected to the video node.
> > Refer to xlnx,csi2rxss.txt for device tree node details.
> >
> > This driver helps configure the number of active lanes to be set, setting
> > and handling interrupts and IP core enable. It logs the number of events
> > occurring according to their type between streaming ON and OFF.
> > It generates a v4l2 event for each short packet data received.
> > The application can then dequeue this event and get the requisite data
> > from the event structure.
> >
> > It adds new V4L2 controls which are used to get the event counter values
> > and reset the subsystem.
> >
> > The Xilinx CSI-2 Rx Subsystem outputs an AXI4 Stream data which can be
> > used for image processing. This data follows the video formats mentioned
> > in Xilinx UG934 when the Video Format Bridge is enabled.
> >
> > v6
> > - 1/2
> >    - Added minor comment by Luca
> >    - Added Reviewed by Rob Herring
> > - 2/2
> >    - No change
> >
> > v5
> > - 1/2
> >    - Removed the DPHY clock description and dt node.
> >    - removed bayer pattern as CSI doesn't deal with it.
> > - 2/2
> >    - removed bayer pattern as CSI doesn't deal with it.
> >    - add YUV422 10bpc media bus format.
> >
> > v4
> > - 1/2
> >    - Added reviewed by Hyun Kwon
> > - 2/2
> >    - Removed irq member from core structure
> >    - Consolidated IP config prints in xcsi2rxss_log_ipconfig()
> >    - Return -EINVAL in case of invalid ioctl
> >    - Code formatting
> >    - Added reviewed by Hyun Kwon
> >
> > v3
> > - 1/2
> >    - removed interrupt parent as suggested by Rob
> >    - removed dphy clock
> >    - moved vfb to optional properties
> >    - Added required and optional port properties section
> >    - Added endpoint property section
> > - 2/2
> >   - Fixed comments given by Hyun.
> >   - Removed DPHY 200 MHz clock. This will be controlled by DPHY driver
> >   - Minor code formatting
> >   - en_csi_v20 and vfb members removed from struct and made local to dt
> parsing
> >   - lock description updated
> >   - changed to ratelimited type for all dev prints in irq handler
> >   - Removed YUV 422 10bpc media format
> >
> > v2
> > - 1/2
> >    - updated the compatible string to latest version supported
> >    - removed DPHY related parameters
> >    - added CSI v2.0 related property (including VCX for supporting upto 16
> >      virtual channels).
> >    - modified csi-pxl-format from string to unsigned int type where the value
> >      is as per the CSI specification
> >    - Defined port 0 and port 1 as sink and source ports.
> >    - Removed max-lanes property as suggested by Rob and Sakari
> >
> > - 2/2
> >    - Fixed comments given by Hyun and Sakari.
> >    - Made all bitmask using BIT() and GENMASK()
> >    - Removed unused definitions
> >    - Removed DPHY access. This will be done by separate DPHY PHY driver.
> >    - Added support for CSI v2.0 for YUV 422 10bpc, RAW16, RAW20 and extra
> >      virtual channels
> >    - Fixed the ports as sink and source
> >    - Now use the v4l2fwnode API to get number of data-lanes
> >    - Added clock framework support
> >    - Removed the close() function
> >    - updated the set format function
> >    - Support only VFB enabled config
> >
> > Vishal Sagar (2):
> >    media: dt-bindings: media: xilinx: Add Xilinx MIPI CSI-2 Rx Subsystem
> >    media: v4l: xilinx: Add Xilinx MIPI CSI-2 Rx Subsystem driver
> >
> >   .../bindings/media/xilinx/xlnx,csi2rxss.txt        |  118 ++
> >   drivers/media/platform/xilinx/Kconfig              |   10 +
> >   drivers/media/platform/xilinx/Makefile             |    1 +
> >   drivers/media/platform/xilinx/xilinx-csi2rxss.c    | 1465
> ++++++++++++++++++++
> >   include/uapi/linux/xilinx-v4l2-controls.h          |   14 +
> >   include/uapi/linux/xilinx-v4l2-events.h            |   25 +
> >   6 files changed, 1633 insertions(+)
> >   create mode 100644
> Documentation/devicetree/bindings/media/xilinx/xlnx,csi2rxss.txt
> >   create mode 100644 drivers/media/platform/xilinx/xilinx-csi2rxss.c
> >   create mode 100644 include/uapi/linux/xilinx-v4l2-events.h
> >