Re: [PATCHv2 1/3] dt-bindings: display: Intel FPGA VIP drm driver Devicetree bindings

["Ong, Hean Loong" <hean.loong.ong-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

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Thanks Neil. 

On Thu, 2017-05-04 at 09:55 +0200, Neil Armstrong wrote:
> On 04/25/2017 04:06 AM, hean.loong.ong@intel.com wrote:
> > 
> > From: "Ong, Hean Loong" <hean.loong.ong@intel.com>
> > 
> > Device tree binding for Intel FPGA Video and Image
> > Processing Suite. The binding involved would be generated
> > from the Altera (Intel) Qsys system. The bindings would
> > set the max width, max height, buts per pixel and memory
> > port width. The device tree binding only supports the Intel
> > Arria10 devkit and its variants. Vendor name retained as
> > altr.
> > 
> > Signed-off-by: Ong, Hean Loong <hean.loong.ong@intel.com>
> > ---
> > v2:
> > * Moved Device Tree bindings to
> > Documentation/devicetree/bindings/display/
> > * Added vendor name altr, to description
> > ---
> >  .../devicetree/bindings/display/altr,vip-fb2.txt   | 30
> > ++++++++++++++++++++++
> >  1 file changed, 30 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/display/altr,vip-fb2.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/display/altr,vip-
> > fb2.txt b/Documentation/devicetree/bindings/display/altr,vip-
> > fb2.txt
> > new file mode 100644
> > index 0000000..bdffefb
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/altr,vip-fb2.txt
> > @@ -0,0 +1,30 @@
> > +Intel Video and Image Processing(VIP) Frame Buffer II bindings
> > +
> > +Supported hardware: Arria 10 and above with display port IP
> > +
> Hi,
> 
> > 
> > +The drm driver for the Arria 10 devkit would require the display
> > resolution
> > +and pixel information to be included as these values are generated
> > based
> > +on the FPGA design that drives the video connector attached to the
> > drm driver
> > +Information the FPGA video IP component can be acquired from
> > +https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/li
> > terature/ug/ug_vip.pdf
> The bindings should not reference the driver, but only the hardware
> and the way it is configured
> and interconnected with the system.
> Please explicit that this is an IP component that can be configured
> with explicit limits on
> the display widths and heights and memory parameters.
> 
> But you should also indicate over what this IP is connected and add a
> port connected to a connector
> node in case this ip is not used on a specific board like in [1] or
> [2] :
> 
> """
> Required nodes:
> 
> The connections to the DU output video ports are modeled using the OF
> graph
> bindings specified in Documentation/devicetree/bindings/graph.txt.
> 
> The following table lists for each supported model the port number
> corresponding to each DU output.
> 
> 		Port 0		Port1		Port2	
> 	Port3
> -------------------------------------------------------------------
> ----------
>  R8A7779 (H1)	DPAD 0		DPAD 1		-	
> 	-
> """
> 
> You may also need to add a "Display Port" connector binding aswell
> along the HDMI, VGA, ....
> 
> I know this targets an FPGA system, so you should explicit that in
> the description.
> 
> > 
> > +Required properties:
> > +
> > +- compatible: "altr,vip-frame-buffer-2.0"
> You should also add model specific compatible strings for each
> supported FPGA devices.
> 
> > 
> > +- reg: Physical base address and length of the framebuffer
> > controller's
> > +  registers.
> > +- altr,max-width: The width of the framebuffer in pixels.
> > +- altr,max-height: The height of the framebuffer in pixels.
> > +- altr,bits-per-symbol: only "8" is currently supported
> > +- altr,mem-port-width = the bus width of the avalon master port on
> > the frame reader
> What is the avalon master port ?
A memory bus that on the FPGA that interfaces with the ARM processor
> Can you add a schema to explicit how this IP is connected to the
> system ?
> 
I could like to include a more detailed schema for the next updated
patch. In the mean time the details of the IP is provided on the links
below:
https://www.altera.com/products/intellectual-property/ip/interface-prot
ocols/m-alt-displayport-megacore.html

https://www.altera.com/documentation/yru1480906794402.html

but basically the idea is:
ARM/Linux -->FPGA(Avalon-MM interface)-->DisplayPort Connector

> > 
> > +
> > +Example:
> > +
> > +	dp_0_frame_buf: vip@100000280 {
> > +			compatible = "altr,vip-frame-buffer-2.0";
> > +			reg = <0x00000001 0x00000280 0x00000040>;
> > +			altr,max-width = <1280>;
> > +			altr,max-height = <720>;
> > +			altr,bits-per-symbol = <8>;
> > +			altr,mem-port-width = <128>;
> > +	};
> > 
> 
> [1] Documentation/devicetree/bindings/display/amlogic,meson-vpu.txt
> [2] Documentation/devicetree/bindings/display/renesas,du.txt
> 
> Thanks,
> 
> Neil
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