Re: [RFC PATCH 3/3] dt-bindings: display: add Amlogic Meson DRM Bindings

[Neil Armstrong]

Hi Laurent,
On 11/28/2016 09:33 AM, Laurent Pinchart wrote:
> Hi Neil,
> 
> Thank you for the patch.
> 
> On Friday 25 Nov 2016 17:03:11 Neil Armstrong wrote:
>> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
>> ---
>>  .../bindings/display/meson/meson-drm.txt           | 134 +++++++++++++++++
>>  1 file changed, 134 insertions(+)
>>  create mode 100644
>> Documentation/devicetree/bindings/display/meson/meson-drm.txt
>>
>> diff --git a/Documentation/devicetree/bindings/display/meson/meson-drm.txt
>> b/Documentation/devicetree/bindings/display/meson/meson-drm.txt new file
>> mode 100644
>> index 0000000..89c1b5f
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/display/meson/meson-drm.txt
>> @@ -0,0 +1,134 @@
>> +Amlogic Meson Display Controller
>> +================================
>> +
>> +The Amlogic Meson Display controller is composed of several components
>> +that are going to be documented below:
>> +
>> +DMC|---------------VPU (Video Processing Unit)------------|------HHI------|
>> +   | vd1   _______     _____________    _____________     |               |
>> +D  |-------|      |----|            |   |            |    |   HDMI PLL    |
>> +D  | vd2   | VIU  |    | Video Post |   | Video Encs |<---|-----VCLK      |
>> +R  |-------|      |----| Processing |   |            |    |               |
>> +   | osd2  |      |    |            |---| Enci ------|----|-----VDAC------|
>> +R  |-------| CSC  |----| Scalers    |   | Encp ------|----|----HDMI-TX----|
>> +A  | osd1  |      |    | Blenders   |   | Encl-------|----|---------------|
>> +M  |-------|______|----|____________|   |____________|    |               |
>> +___|______________________________________________________|_______________|
>> +
>> +
>> +VIU: Video Input Unit
>> +---------------------
>> +
>> +The Video Input Unit is in charge of the pixel scanout from the DDR memory.
>> +It fetches the frames addresses, stride and parameters from the "Canvas"
>> memory.
>> +This part is also in charge of the CSC (Colorspace Conversion).
>> +It can handle 2 OSD Planes and 2 Video Planes.
>> +
>> +VPP: Video Processing Unit
> 
> Do you mean "Video Post Processing" ? In your diagram above Video Processing 
> Unit is abbreviated VPU and covers the VIU, VPP and encoders.

Exact, I meant VPP here.

> 
>> +--------------------------
>> +
>> +The Video Processing Unit is in charge if the scaling and blending of the
>> +various planes into a single pixel stream.
>> +There is a special "pre-blending" used by the video planes with a dedicated
>> +scaler and a "post-blending" to merge with the OSD Planes.
>> +The OSD planes also have a dedicated scaler for one of the OSD.
>> +
>> +VENC: Video Encoders
>> +--------------------
>> +
>> +The VENC is composed of the multiple pixel encoders :
>> + - ENCI : Interlace Video encoder for CVBS and Interlace HDMI
>> + - ENCP : Progressive Video Encoder for HDMI
>> + - ENCL : LCD LVDS Encoder
>> +The VENC Unit gets a Pixel Clocks (VCLK) from a dedicated HDMI PLL and
>> clock
>> +tree and provides the scanout clock to the VPP and VIU.
>> +The ENCI is connected to a single VDAC for Composite Output.
>> +The ENCI and ENCP are connected to an on-chip HDMI Transceiver.
>> +
>> +Device Tree Bindings:
>> +---------------------
>> +
>> +VPU: Video Processing Unit
>> +--------------------------
>> +
>> +Required properties:
>> + - compatible: value should be different for each SoC family as :
>> + 	- GXBB (S905) : "amlogic,meson-gxbb-vpu"
>> + 	- GXL (S905X, S905D) : "amlogic,meson-gxl-vpu"
>> + 	- GXM (S912) : "amlogic,meson-gxm-vpu"
>> +	followed by the common "amlogic,meson-gx-vpu"
>> + - reg: base address and size of he following memory-mapped regions :
>> +	- vpu
>> +	- hhi
>> +	- dmc
>> + - reg-names: should contain the names of the previous memory regions
>> + - interrupts: should contain the VENC Vsync interrupt number
>> +
>> +- ports: A ports node with endpoint definitions as defined in
>> +  Documentation/devicetree/bindings/media/video-interfaces.txt. The
>> +  second port should be the output endpoints for VENC connectors.
>> +
>> +VENC CBVS Output
>> +----------------------
>> +
>> +The VENC can output Composite/CVBS output via a decicated VDAC.
>> +
>> +Required properties:
>> +  - compatible: value must be one of:
>> + - compatible: value should be different for each SoC family as :
> 
> One of those two lines is redundant.

Will fix.

> 
>> + 	- GXBB (S905) : "amlogic,meson-gxbb-venc-cvbs"
>> + 	- GXL (S905X, S905D) : "amlogic,meson-gxl-venc-cvbs"
>> + 	- GXM (S912) : "amlogic,meson-gxm-venc-cvbs"
>> +	followed by the common "amlogic,meson-gx-venc-cvbs"
>> +
> 
> No registers ? Are the encoders registers part of the VPU register space, 
> intertwined in a way that they can't be specified separately here ?

Exact, all the video registers on the Amlogic SoC are part of a long history of fixup/enhance from very old SoCs, it's
quite hard to distinguish a Venc registers array since they are mixed with the multiple encoders registers...

The only separate registers are the VDAC and HDMI PHY, I may move them to these separate nodes since they are part of the HHI register space.

It is a problem if I move them in the next release ? Next release will certainly have HDMI support, and will have these refactorings.

> 
>> +- ports: A ports node with endpoint definitions as defined in
>> +  Documentation/devicetree/bindings/media/video-interfaces.txt. The
>> +  first port should be the input endpoints, connected ot the VPU node.
>> +
>> +Example:
>> +
>> +venc_cvbs: venc-cvbs {
>> +	compatible = "amlogic,meson-gxbb-venc-cvbs";
>> +	status = "okay";
>> +
>> +	ports {
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +
>> +		enc_cvbs_in: port@0 {
>> +			 #address-cells = <1>;
>> +			 #size-cells = <0>;
>> +			 reg = <0>;
>> +
>> +			 venc_cvbs_in_vpu: endpoint@0 {
>> +				 reg = <0>;
>> +				 remote-endpoint = <&vpu_out_venc_cvbs>;
>> +			};
>> +		};
>> +	};
>> +};
>> +
>> +vpu: vpu@d0100000 {
>> +	compatible = "amlogic,meson-gxbb-vpu";
>> +	reg = <0x0 0xd0100000 0x0 0x100000>,
>> +	      <0x0 0xc883c000 0x0 0x1000>,
>> +	      <0x0 0xc8838000 0x0 0x1000>;
>> +	reg-names = "base", "hhi", "dmc";
>> +	interrupts = <GIC_SPI 3 IRQ_TYPE_EDGE_RISING>;
>> +
>> +	ports {
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +
>> +		vpu_out: port@1 {
>> +			 #address-cells = <1>;
>> +			 #size-cells = <0>;
>> +			 reg = <1>;
>> +
>> +			 vpu_out_venc_cvbs: endpoint@0 {
>> +				 reg = <0>;
>> +				 remote-endpoint = <&venc_cvbs_in_vpu>;
>> +			 };
>> +		 };
>> +	};
>> +};
> 

Thanks for the review !

Neil