Hi
I wrote linux drm encoder driver for hdmi of digilent's zybo z7 board
The below figure is vivado design which uses digilent's custom ips(axi_dynclk_0, rgb2dvi_0) for dynamic clocks generation and tmds signal generations
This is devicetree
/delete-node/ &misc_clk_0;
&axi_dynclk_0 {
compatible = "digilent,axi-dynclk";
#clock-cells = <0>;
clocks = <&clkc 16>;
};
&v_frmbuf_rd_0 {
reset-gpios = <&gpio0 54 1>;
};
&v_tc_0 {
compatible = "xlnx,bridge-v-tc-6.1";
xlnx,pixels-per-clock = <1>;
clocks = <&axi_dynclk_0>, <&clkc 15>;
};
&amba {
digilent_encoder {
compatible = "digilent,drm-hdmi";
digilent,fmax = <150000>;
digilent,edid-i2c = <&i2c0>;
#address-cell = <1>;
#size-cell = <0>;
port@0 {
reg = <0>;
hdmi_encoder: endpoint {
remote-endpoint = <&dmaengine_crtc>;
};
};
};
drm-pl_disp-drv {
compatible = "xlnx,pl-disp";
dmas = <&v_frmbuf_rd_0 0>;
dma-names = "dma0";
xlnx,vformat = "BG24";
xlnx,bridge = <&v_tc_0>;
#address-cells = <1>;
#size-cells = <0>;
port@0 {
reg = <0>;
dmaengine_crtc: endpoint {
remote-endpoint = <&hdmi_encoder>;
};
};
};
};
When I used the original xlnx_pl_disp, it was not probed because it failed to request dma
xilinx-frmbuf 43c00000.v_frmbuf_rd: Xilinx AXI frmbuf DMA_MEM_TO_DEV xilinx-frmbuf 43c00000.v_frmbuf_rd: Xilinx AXI FrameBuffer Engine Driver Probed!! xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx-pl-disp amba:drm-pl_disp-drv: Didn't get vtc bridge instance xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx-pl-disp amba:drm-pl_disp-drv: failed to request dma channel xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 digilent_drm_hdmi: loading out-of-tree module taints kernel. digilent-drm-hdmi amba:digilent_encoder: No max horizontal width in DT, using default 1920 digilent-drm-hdmi amba:digilent_encoder: No max vertical height in DT, using default 1080 digilent-drm-hdmi amba:digilent_encoder: Digilent HDMI DRM Driver probed 0 xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: Xilinx VTC IP version : 0x0602000b xlnx,bridge-vtc 43c20000.v_tc: Xilinx VTC DRM Bridge driver probed
I could figure out that it was because the driver requested the acquired dma in the previous failed probe again through the following investigation
$ cat /sys/class/dma/dma1chan0/device/of_node/name v_frmbuf_rd $ cat /sys/class/dma/dma1chan0/in_use 1
I can fix it with my patch for xlnx_pl_disp which releases dma when it failed to probe due to deferred bridge vtc
The following shows successful log
xilinx-frmbuf 43c00000.v_frmbuf_rd: Xilinx AXI frmbuf DMA_MEM_TO_DEV xilinx-frmbuf 43c00000.v_frmbuf_rd: Xilinx AXI FrameBuffer Engine Driver Probed!! xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx-pl-disp amba:drm-pl_disp-drv: Didn't get vtc bridge instance xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx-pl-disp amba:drm-pl_disp-drv: Didn't get vtc bridge instance xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx-pl-disp amba:drm-pl_disp-drv: Didn't get vtc bridge instance xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx-pl-disp amba:drm-pl_disp-drv: Didn't get vtc bridge instance digilent_drm_hdmi: loading out-of-tree module taints kernel. digilent-drm-hdmi amba:digilent_encoder: No max horizontal width in DT, using default 1920 digilent-drm-hdmi amba:digilent_encoder: No max vertical height in DT, using default 1080 digilent-drm-hdmi amba:digilent_encoder: Digilent HDMI DRM Driver probed 0 xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: failed to get video clk -517 xlnx-pl-disp amba:drm-pl_disp-drv: Didn't get vtc bridge instance xlnx,bridge-vtc 43c20000.v_tc: vtc ppc = 1 xlnx,bridge-vtc 43c20000.v_tc: Xilinx VTC IP version : 0x0602000b xlnx,bridge-vtc 43c20000.v_tc: Xilinx VTC DRM Bridge driver probed [drm] Supports vblank timestamp caching Rev 2 (21.10.2013). [drm] No driver support for vblank timestamp query. xlnx-drm xlnx-drm.0: bound amba:drm-pl_disp-drv (ops 0xc073dad0) xlnx-drm xlnx-drm.0: bound amba:digilent_encoder (ops hdmi_drm_driver_exit [digilent_drm_hdmi]) Console: switching to colour frame buffer device 100x30 xlnx-pl-disp amba:drm-pl_disp-drv: fb0: frame buffer device [drm] Initialized xlnx 1.0.0 20130509 for amba:drm-pl_disp-drv on minor 0 xlnx-pl-disp amba:drm-pl_disp-drv: Xlnx PL display driver probed