Mobile display processor： MDP 3.05 for display processing

DCS (DisplayCommandSet)：DCS是一個標準化的命令集，用於命令模式的顯示模組

1.     硬體原理圖

圖1

GPIO_24引腳功能是MDP verticalsync – primary Configurable I/O，如果我們有第2個顯示屏，還會用到GPIO_25引腳MDP vertical sync –secondary Configurable I/O，這裡我們只用到GPIO_24。

TP和背光部分後面再介紹。

2.     支援ili9806e顯示屏

Before starting any porting, verify thatyou are using the latest Android device tree and Qualcomm’s proprietary source.How to generate Panel dtsi/header file: Take these steps to update the XMLfiles for display.

參考device\qcom\common\display\tools\README.txt

2.1   生成panel dtsi/標頭檔案

參考device/qcom/common/display/tools/README.txt檔案，以tools資料夾下的《dsi-panel-nt35596-1080p-video.dtsi》為樣本，我們複製一份並命名為取名為panel_ili9806e_wvga_video.xml，根據ili9806e及原理圖修改其中的內容然後用命令：perl parser.pl panel_ili9806e_wvga_video.xml panel生成dsi-panel-ili9806e-wvga-video.dtsi和panel_ili9806e-wvga-video.h檔案

這裡我們重點介紹如何根據顯示屏驅動IC廠家給的初始化程式碼來填寫panel_ili9806e_wvga_video.xml檔案

(1)  上電初始化部分

//***************Page 1 Command******************************//

REGISTER,FF,5,FF,98,06,04,01     //Change to Page 1

REGISTER,08,1,10                 // output SDA

REGISTER,21,1,01                 // DE = 1 Active

REGISTER,30,1,02                 // 480 X 800

…

在bootable/bootloader/lk/dev/gcdb/display/include/找到自帶的檔案panel_ili9806e_fwvga_video.h可知初始化的mipi包資料型別為0x39，見下圖：

圖2

根據初始化程式碼填寫的panel_ili9806e_wvga_video.xml上電初始化內容如下：

圖3

上圖對應的結構體如下：

kernel\drivers\video\msm\mdss\mdss_dsi_cmd.h

struct dsi_ctrl_hdr {
       chardtype;   /* data type */
       charlast;      /* last in chain */
       charvc; /* virtual chan */
       charack;      /* ask ACK from peripheral */
       charwait;     /* ms */
       shortdlen;    /* 16 bits */
} __packed;
 
struct dsi_cmd_desc {
       structdsi_ctrl_hdr dchdr;
       char*payload;
};

(2)  MIPI DSI介面

根據原理圖知道採用的是DSI介面，

採用MIPIDSI Interface介面

? DSI相容的外設支援Command或Video操作模式，用哪個模式由外設的構架決定

? Command模式是指採用傳送命令和資料到具有顯示快取的控制器。主機通過命令間接的控制外設。Command模式採用雙向介面

? Video模式是指從主機傳輸到外設採用時實象素流。這種模式只能以高速傳輸。為減少複雜性和節約成本，只採用Video模式的系統可能只有一個單向資料路徑

? Command Mode（類似於MPU介面）

   ? Video Mode（類似於RGB介面）- 必須用高速模式傳輸資料

command還是video模式由Driver IC RAM決定：

  1.帶RAM IC可支援 command及video模式

  2.不帶RAM IC只支援video模式

 ILI9806E不帶RAM.

2.2   Lk支援ili9806e顯示屏

(1)  增加顯示屏標頭檔案

拷貝上面生成的panel_ili9806e-wvga-video.h檔案到

bootable/bootloader/lk/dev/gcdb/display/include/目錄下。

(2)  bootable\bootloader\lk\target\msm8909\oem_panel.c增加對新顯示屏的支援

#include "include/panel_ili9806e_wvga_video.h"
enum {
       HX8394D_720P_VIDEO_PANEL,
       SHARP_QHD_VIDEO_PANEL,
       TRULY_WVGA_CMD_PANEL,
       HX8379A_FWVGA_SKUA_VIDEO_PANEL,
       ILI9806E_FWVGA_VIDEO_PANEL,
       ILI9806E_WVGA_VIDEO_PANEL,//kandi add at 2015.11.26
       HX8394D_QHD_VIDEO_PANEL,
       HX8379C_FWVGA_VIDEO_PANEL,
       NT35512_FWVGA_VIDEO_PANEL,
       OTM9605A_QHD_VIDEO_PANEL,
       OTM9605A_QHD_CB03_VIDEO_PANEL,
       OTM9605AG_QHD_VIDEO_PANEL,
       HX8389B_QHD_VIDEO_PANEL,
       HX8389BG_QHD_VIDEO_PANEL,
       JD9161BA_FWVGA_VIDEO_PANEL,
       UNKNOWN_PANEL
};

init_panel_data()函式增加：

case ILI9806E_WVGA_VIDEO_PANEL:
                panelstruct->paneldata    = &ili9806e_wvga_video_panel_data;
                panelstruct->panelres     = &ili9806e_wvga_video_panel_res;
                panelstruct->color        = &ili9806e_wvga_video_color;
                panelstruct->videopanel   = &ili9806e_wvga_video_video_panel;
                panelstruct->commandpanel =&ili9806e_wvga_video_command_panel;
                panelstruct->state        = &ili9806e_wvga_video_state;
                panelstruct->laneconfig   = &ili9806e_wvga_video_lane_config;
                panelstruct->paneltiminginfo
                                         =&ili9806e_wvga_video_timing_info;
                panelstruct->panelresetseq
                                         =&ili9806e_wvga_video_reset_seq;
                panelstruct->backlightinfo =&ili9806e_wvga_video_backlight;
                pinfo->mipi.panel_cmds
                                        =ili9806e_wvga_video_on_command;
               pinfo->mipi.num_of_panel_cmds
                                        =ILI9806E_WVGA_VIDEO_ON_COMMAND;
                memcpy(phy_db->timing,
                               ili9806e_wvga_video_timings, TIMING_SIZE);
                pinfo->mipi.signature =ILI9806E_WVGA_VIDEO_SIGNATURE;
                 panelstruct->paneldata->panel_lp11_init= 1;
                break;

oem_panel_select()函式的QRD_SKUE_CB03這case改為用新顯示屏

case QRD_SKUE_CB03:
              //panel_id= HX8389BG_QHD_VIDEO_PANEL;
              //panel_id= OTM9605A_QHD_CB03_VIDEO_PANEL;
              panel_id= ILI9806E_WVGA_VIDEO_PANEL; //kandi add at 2015.11.26
              //panel_id= NT35512_FWVGA_VIDEO_PANEL;
              break;

2.3   Kernel支援ili9806e顯示屏

(1)  增加顯示屏對應的裝置樹

拷貝上面生成的dsi-panel-ili9806e-wvga-video.dtsi到

kernel\arch\arm\boot\dts\qcom目錄下

(2)  kernel\arch\arm\boot\dts\qcom\msm8909-qrd-skue-cb03.dtsi需要包含dsi-panel-ili9806e-wvga-video.dtsi

#include"dsi-panel-ili9806e-wvga-video.dtsi"
 
&mdss_mdp {
       qcom,mdss-pref-prim-intf= "dsi";//DSI設定成主要介面
};
 
//&dsi_otm9605a_qhd_video {
//    qcom,cont-splash-enabled;
//};
 
&pmx_mdss {
       qcom,num-grp-pins= <1>;
       qcom,pins= <&gp 8>;
};
 
&pmx_mdss_te {
       qcom,num-grp-pins= <1>;
       qcom,pins= <&gp 24>;
};
 
&mdss_dsi0 {
//    qcom,dsi-pref-prim-pan= <&dsi_otm9605a_qhd_video>;
       qcom,dsi-pref-prim-pan= <&dsi_ili9806e_wvga_video>;//設定PANEL NODE
       pinctrl-names= "mdss_default", "mdss_sleep";
       pinctrl-0= <&mdss_dsi_active &mdss_te_active>;
       pinctrl-1= <&mdss_dsi_suspend &mdss_te_suspend>;
 
       qcom,platform-reset-gpio= <&msm_gpio 8 0>;
};

需要主要dsi_ili9806e_wvga_video需要和顯示屏的dsi-panel-ili9806e-wvga-video.dtsi中的值一樣，如下：

&mdss_mdp {
       dsi_ili9806e_wvga_video:qcom,mdss_dsi_ili9806e_wvga_video {
              qcom,mdss-dsi-panel-name= "ili9806e wvga video mode dsi panel";
…
}
}

(3)  kernel\arch\arm\boot\dts\qcom\msm8909-mdss.dtsi

&soc {
      mdss_mdp: qcom,[email protected] { //包含mdss_mdp
          compatible = "qcom,mdss_mdp";
          ...
      }
     mdss_dsi0: qcom,[email protected] { //包含mdss_dsi0
        compatible = "qcom,mdss-dsi-ctrl";
        ...
     }
   }

做上面的修改後分別編譯bootloader和kernel

make aboot

make bootimage

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