LCD模块如何建立联系分析

本文主要是基于rk3566/rk3568平台通过LCD uboot 和 设备树 的代码 对 vop - encoder/connector - panel 三者如何建立联系的进行分析。

一、设备树部分

设备树主要是借助remote-endpoint属性来达到选择相应的外设配置。

1、display-subsystem的设备树信息

1）以ports属性指定相应的vop端点

2）以route_dsi0 指定uboot 阶段的logo配置，其中的connect属性指定的vop需与ports的一致。

        display_subsystem: display-subsystem {                compatible = "rockchip,display-subsystem";                memory-region = <&drm_logo>, <&drm_cubic_lut>;                memory-region-names = "drm-logo", "drm-cubic-lut";                ports = <&vop_out>;                devfreq = <&dmc>;                route {                        route_dsi0: route-dsi0 {                                status = "okay";                                logo,uboot = "logo.bmp";                                logo,kernel = "logo_kernel.bmp";                                logo,mode = "center";                                charge_logo,mode = "center";                                connect = <&vp0_out_dsi0>;                        };                };        };

2、vop的设备树信息 

1）以ports -> port -> endpoint -> remote-endpoint 的顺序，通过remote-endpoint 属性来指定远端的设备端点

       vop: [email protected] {                compatible = "rockchip,rk3568-vop";                reg = <0x0 0xfe040000 0x0 0x3000>, <0x0 0xfe044000 0x0 0x1000>;                reg-names = "regs", "gamma_lut";                rockchip,grf = <&grf>;                interrupts = <GIC_SPI 148 IRQ_TYPE_LEVEL_HIGH>;                clocks = <&cru ACLK_VOP>, <&cru HCLK_VOP>, <&cru DCLK_VOP0>, <&cru DCLK_VOP1>, <&cru DCLK_VOP2>;                clock-names = "aclk_vop", "hclk_vop", "dclk_vp0", "dclk_vp1", "dclk_vp2";                iommus = <&vop_mmu>;                power-domains = <&power RK3568_PD_VO>;                status = "okay";                vop_out: ports {                        #address-cells = <1>;                        #size-cells = <0>;                        vp0: [email protected] {                                #address-cells = <1>;                                #size-cells = <0>;                                reg = <0>;                                vp0_out_dsi0: [email protected] {                                        reg = <0>;                                        remote-endpoint = <&dsi0_in_vp0>;                                };                                vp0_out_dsi1: [email protected] {                                        reg = <1>;                                        remote-endpoint = <&dsi1_in_vp0>;                                };                                vp0_out_edp: [email protected] {                                        reg = <2>;                                        remote-endpoint = <&edp_in_vp0>;                                };                                vp0_out_hdmi: [email protected] {                                        reg = <3>;                                        remote-endpoint = <&hdmi_in_vp0>;                                };                        };                };        };

3、dsi的设备树信息

1）dsi -> ports -> port dsi0_in_vp0(endpoint) 下的remote-endpoint 为dsi与vop间建立关系的属性配置，其中dsi作为输入端，另一端接的是vop out端。

2）dsi -> ports -> port -> dsi_out_panel1/dsi_out_panel2/dsi_out_panel3(endpoint)下的remote-endpoint 为dsi 与 panel 间建立关系的属性配置。此处代表有三个panel。因此 若想多屏可以在此处增加节点达到和新panel建立联系。

3）dsi->panel 为panel的配置。正常是单独创建个屏dtsi文件后，在文件中引用（&dsi0) 来进行新增屏。此处只是为了更好的分析而集成在一起（本身设备树在编译的时候也是覆盖的操作）。

4）dsi -> panel -> ports -> port -> panel1_in_dsi(endpoint) 下的remote-endpoint 为panel与dsi间的关系，即此处是连到dsi_out_panel1上。

dsi0: [email protected] {                compatible = "rockchip,rk3568-mipi-dsi";                reg = <0x0 0xfe060000 0x0 0x10000>;                interrupts = <GIC_SPI 68 IRQ_TYPE_LEVEL_HIGH>;                clocks = <&cru PCLK_DSITX_0>, <&cru HCLK_VO>, <&video_phy0>;                clock-names = "pclk", "hclk", "hs_clk";                resets = <&cru SRST_P_DSITX_0>;                reset-names = "apb";                phys = <&video_phy0>;                phy-names = "mipi_dphy";                power-domains = <&power RK3568_PD_VO>;                rockchip,grf = <&grf>;                #address-cells = <1>;                #size-cells = <0>;                status = "okay";                ports {                        #address-cells = <1>;                        #size-cells = <0>;                        dsi0_in: [email protected] {                                reg = <0>;                                #address-cells = <1>;                                #size-cells = <0>;                                dsi0_in_vp0: [email protected] {                                        reg = <0>;                                        remote-endpoint = <&vp0_out_dsi0>;                                        status = "okay";                                };                                dsi0_in_vp1: [email protected] {                                        reg = <1>;                                        remote-endpoint = <&vp1_out_dsi0>;                                        status = "disabled";                                };                        };                        [email protected] {                                reg = <1>;                                dsi_out_panel1: endpoint {                                        remote-endpoint = <&panel1_in_dsi>;                                };                        };                        [email protected] {                                reg = <2>;                                dsi_out_panel2: endpoint {                                        remote-endpoint = <&panel2_in_dsi>;                                };                        };                        [email protected] {                                reg = <3>;                                dsi_out_panel3: endpoint {                                        remote-endpoint = <&panel3_in_dsi>;                                };                        };                };                [email protected] {                        status = "okay";                        compatible = "simple-panel-dsi";                        reg = <0>;                        num = <0>;                        lcd-ic = "st7703";                        lcd-vendor = "hbs";                        id = [24];                        id-reg = <0xDA>;                        power-supply = <&vcc3v3_lcd0_n>;                        reset-gpios = <&gpio3 RK_PD1 GPIO_ACTIVE_LOW>;                        enable-gpios = <&gpio0 RK_PD5 GPIO_ACTIVE_HIGH>;                        //backlight = <&backlight>;                        reset-delay-ms = <60>;                        enable-delay-ms = <60>;                        prepare-delay-ms = <60>;                        unprepare-delay-ms = <60>;                        disable-delay-ms = <60>;                        init-delay-ms = <60>;                        dsi,flags = <(MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |                                MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_EOT_PACKET)>;                        dsi,format = <MIPI_DSI_FMT_RGB888>;                        dsi,lanes  = <4>;                        panel-init-sequence = [                                39 00 04 B9 F1 12 83                                39 00 05 B1 00 00 00 DA                                ...                                ...                                13 FA 02 11 00                                13 32 02 29 00                        ];                        panel-exit-sequence = [                                05 32 01 28                                05 FA 01 10                        ];                        display-timings {                                native-mode = <&dsi0_timing2>;                                dsi0_timing2: timing0 {                                        clock-frequency = <55230000>;                                        hactive = <720>;                                        vactive = <1280>;                                        hfront-porch = <50>;                                        hsync-len = <20>;                                        hback-porch = <50>;                                        vfront-porch = <15>;                                        vsync-len = <5>;                                        vback-porch = <15>;                                        hsync-active = <0>;                                        vsync-active = <0>;                                        de-active = <0>;                                        pixelclk-active = <1>;                                };                        };                        ports {                                #address-cells = <1>;                                #size-cells = <0>;                                [email protected] {                                        reg = <0>;                                        panel1_in_dsi: endpoint {                                                remote-endpoint = <&dsi_out_panel1>;                                         };                                };                        };                };                [email protected] {                        status = "okay";                        compatible = "simple-panel-dsi";                        reg = <0>;                        num = <1>;                        id = [15];                        id-reg = <0xDA>;                        power-supply = <&vcc3v3_lcd0_n>;                        reset-gpios = <&gpio3 RK_PD1 GPIO_ACTIVE_LOW>;                        enable-gpios = <&gpio0 RK_PD5 GPIO_ACTIVE_HIGH>;                        //backlight = <&backlight>;                        reset-delay-ms = <60>;                        enable-delay-ms = <60>;                        prepare-delay-ms = <60>;                        unprepare-delay-ms = <60>;                        disable-delay-ms = <60>;                        init-delay-ms = <60>;                        dsi,flags = <(MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |                                MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_EOT_PACKET)>;                        dsi,format = <MIPI_DSI_FMT_RGB888>;                        dsi,lanes  = <4>;                        panel-init-sequence = [                                39 00 04 B9 F1 12 83                                ...                                ...                                13 78 02 11 00                                13 0A 02 29 00                        ];                        panel-exit-sequence = [                                05 0A 01 28                                05 78 01 10                        ];                        display-timings {                                native-mode = <&dsi0_timing1>;                                dsi0_timing1: timing0 {                                        clock-frequency = <62640000>;                                        hactive = <720>;                                        vactive = <1280>;                                        hfront-porch = <10>;                                        hsync-len = <25>;                                        hback-porch = <45>;                                        vfront-porch = <10>;                                        vsync-len = <4>;                                        vback-porch = <11>;                                        hsync-active = <0>;                                        vsync-active = <0>;                                        de-active = <0>;                                        pixelclk-active = <1>;                                };                        };                        ports {                                #address-cells = <1>;                                #size-cells = <0>;                                [email protected] {                                        reg = <0>;                                        panel2_in_dsi: endpoint {                                                remote-endpoint = <&dsi_out_panel2>;                                        };                                };                        };                };        };

 二、uboot部分

uboot部分主要是打算借助uboot上解析设备树部分的代码来进行分析。

1、通过ofnode_for_each_subnode遍历route节点下的子节点，即为route-dsi0。

2、通过route-dsi0 -> connect的属性值来定位到vop上的节点vp0_out_dsi0。

3、找到vop的节点后，通过uclass_get_device_by_ofnode启动vop设备，最终会执行到相应的rockchip_vop_probe函数（正常下，使用U_BOOT_DRIVER只会回调bind函数，而不会执行probe的）。

4、在执行到rockchip_of_find_connector函数时，实际传进的参数为vop节点下的vp0_out_dsi0。

static int rockchip_display_probe(struct udevice *dev){    ...//省略掉无关代码    ...route_node = dev_read_subnode(dev, "route");if (!ofnode_valid(route_node))return -ENODEV;ofnode_for_each_subnode(node, route_node) {if (!ofnode_is_available(node))continue;phandle = ofnode_read_u32_default(node, "connect", -1);if (phandle < 0) {printf("Warn: can't find connect node's handle");continue;}ep_node = of_find_node_by_phandle(phandle);if (!ofnode_valid(np_to_ofnode(ep_node))) {printf("Warn: can't find endpoint node from phandle");continue;}port_node = of_get_parent(ep_node);if (!ofnode_valid(np_to_ofnode(port_node))) {printf("Warn: can't find port node from phandle");continue;}port_parent_node = of_get_parent(port_node);if (!ofnode_valid(np_to_ofnode(port_parent_node))) {printf("Warn: can't find port parent node from phandle");continue;}is_ports_node = strstr(port_parent_node->full_name, "ports") ? 1 : 0;if (is_ports_node) {vop_node = of_get_parent(port_parent_node);if (!ofnode_valid(np_to_ofnode(vop_node))) {printf("Warn: can't find crtc node from phandle");continue;}} else {vop_node = port_parent_node;}ret = uclass_get_device_by_ofnode(UCLASS_VIDEO_CRTC,  np_to_ofnode(vop_node),  &crtc_dev);if (ret) {printf("Warn: can't find crtc driver %d", ret);continue;}crtc = (struct rockchip_crtc *)dev_get_driver_data(crtc_dev);conn_dev = rockchip_of_find_connector(np_to_ofnode(ep_node));if (!conn_dev) {printf("Warn: can't find connect driver");continue;}conn = (const struct rockchip_connector *)dev_get_driver_data(conn_dev);phy = rockchip_of_find_phy(conn_dev);bridge = rockchip_of_find_bridge(conn_dev);if (bridge)panel = rockchip_of_find_panel(bridge->dev);elsepanel = rockchip_of_find_panel(conn_dev);        ...    ...// 省略掉无关代码return 0;}

5、 通过子节点获取父节点的操作来定位，因此rockchip_of_find_connector函数下的conn即为dsi0节点，因此再次通过uclass_get_device_by_ofnode来加载dsi设备，即会调用dw_mipi_dsi_probe函数。

static struct udevice *rockchip_of_find_connector(ofnode endpoint){ofnode ep, port, ports, conn;uint phandle;struct udevice *dev;int ret;if (ofnode_read_u32(endpoint, "remote-endpoint", &phandle))return NULL;ep = ofnode_get_by_phandle(phandle);if (!ofnode_valid(ep) || !ofnode_is_available(ep))return NULL;port = ofnode_get_parent(ep);if (!ofnode_valid(port))return NULL;ports = ofnode_get_parent(port);if (!ofnode_valid(ports))return NULL;conn = ofnode_get_parent(ports);if (!ofnode_valid(conn) || !ofnode_is_available(conn))return NULL;ret = uclass_get_device_by_ofnode(UCLASS_DISPLAY, conn, &dev);if (ret)return NULL;return dev;}

 6、rockchip_of_find_bridge查找是否存在bridge设备

static struct rockchip_bridge *rockchip_of_find_bridge(struct udevice *conn_dev){ofnode node, ports, port, ep;struct udevice *dev;int ret;ports = dev_read_subnode(conn_dev, "ports");if (!ofnode_valid(ports))return NULL;ofnode_for_each_subnode(port, ports) {u32 reg;if (ofnode_read_u32(port, "reg", &reg))continue;if (reg != PORT_DIR_OUT)continue;ofnode_for_each_subnode(ep, port) {ofnode _ep, _port, _ports;uint phandle;if (ofnode_read_u32(ep, "remote-endpoint", &phandle))continue;_ep = ofnode_get_by_phandle(phandle);if (!ofnode_valid(_ep))continue;_port = ofnode_get_parent(_ep);if (!ofnode_valid(_port))continue;_ports = ofnode_get_parent(_port);if (!ofnode_valid(_ports))continue;node = ofnode_get_parent(_ports);if (!ofnode_valid(node))continue;ret = uclass_get_device_by_ofnode(UCLASS_VIDEO_BRIDGE,  node, &dev);if (!ret)goto found;}}return NULL;found:return (struct rockchip_bridge *)dev_get_driver_data(dev);}

7、在dsi0的节点下，通过ports -> port -> remote-endpoint来找到[email protected]/2/3节点下的port 的endpoint节点，再依次通过获取父节点的方式获取到panel的节点，最后通过uclass_get_device_by_ofnode函数启动panel，即执行rockchip_panel_probe回调 

static struct rockchip_panel *rockchip_of_find_panel(struct udevice *dev){ofnode panel_node, ports, port, ep, port_parent_node;struct udevice *panel_dev;int ret;panel_node = dev_read_subnode(dev, "panel");if (ofnode_valid(panel_node) && ofnode_is_available(panel_node)) {ret = uclass_get_device_by_ofnode(UCLASS_PANEL, panel_node,  &panel_dev);if (!ret)goto found;}ports = dev_read_subnode(dev, "ports");if (!ofnode_valid(ports))return NULL;ofnode_for_each_subnode(port, ports) {u32 reg;if (ofnode_read_u32(port, "reg", &reg))continue;if (reg != PORT_DIR_OUT)continue;ofnode_for_each_subnode(ep, port) {ofnode _ep, _port;uint phandle;bool is_ports_node = false;if (ofnode_read_u32(ep, "remote-endpoint", &phandle))continue;_ep = ofnode_get_by_phandle(phandle);if (!ofnode_valid(_ep))continue;_port = ofnode_get_parent(_ep);if (!ofnode_valid(_port))continue;port_parent_node = ofnode_get_parent(_port);is_ports_node = strstr(port_parent_node.np->full_name, "ports") ? 1 : 0;if (is_ports_node)panel_node = ofnode_get_parent(port_parent_node);elsepanel_node = ofnode_get_parent(_port);if (!ofnode_valid(panel_node))continue;ret = uclass_get_device_by_ofnode(UCLASS_PANEL,  panel_node,  &panel_dev);if (!ret)goto found;}}return NULL;found:return (struct rockchip_panel *)dev_get_driver_data(panel_dev);}

三、总结

1、由设备树分析可知：在display-subsystem 下通过ports -> port ->endpoint -> remote-endpoint的方式来实现建立vop - dsi - panel 的联系

2、由uboot分析可知：在rockchip_display_probe中先解析对应设备树节点，通过dev_read_subnode、of_find_node_by_phandle、of_get_parent、uclass_get_device_by_xxx（uclass_get_device_by_ofnode）等系列函数去启动vop 、connector(dsi）、panel等设备。

如下：整体的框架

 注：

1）vop *（video out processor）代表有多个处理器时的情况。

2）panel* 是代表存在多屏情况下的因素。