Android Qcom Display学习(十一)

该系列文章总目录链接与各部分简介： Android Qcom Display学习(零)
本章主要是基于MIPI Payload传输接口的学习，包括Generic和DCS的接口不同。

底层都是基于dsi_ctrl_cmd_transfer去封装的，下面第一部分调用原生接口，第二部分分析高通是如何进行读写操作的

Generic

MIPI Generic和DCS指令的区别在于DCS会将CMD作为data[0]传入，即使根据size的type会有不同，但到最后还是只有两类
mipi_dsi_packet_format_is_short or mipi_dsi_packet_format_is_long，DCS会有标准命令集，理论上Generic应该是兼容，为了一些屏客制化的部分。

mipi_dsi_generic_write/mipi_dsi_generic_read \
                                              —— mipi_dsi_device_transfer —— dsi_host_transfer —— dsi_ctrl_cmd_transfer
mipi_dsi_dcs_read/mipi_dsi_dcs_write         /

Generic:
 mipi_dsi_generic_write(dsi, (u8[]){0xB0, 0x00}, 2);
 struct mipi_dsi_msg msg = {
 	.channel = dsi->channel,
 	.tx_buf = data,
 	.tx_len = len
 };
 msg.type = MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM; size = 2
 
DCS:
 u8 payload[2] = { brightness & 0xff, brightness >> 8 };
 mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS, payload, sizeof(payload));
    size = len + 1;
    t[0] = cmd;       //data[0] 作为cmd
	memcpy(&tx[1], data, len);
    msg.type = MIPI_DSI_DCS_LONG_WRITE;  //size = 3
 
 DCS标准化命令集 /* MIPI DCS commands */
	MIPI_DCS_SET_DISPLAY_BRIGHTNESS = 0x51,		适用于OLED等CMD屏   DCS控制背光 bl_ctrl_dcs
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Test Interface

(1)测试Generic的函数接口，发现没有值返回

u8 data = 0;
u8 data2 = 0;
rc = mipi_dsi_generic_read(&(display->panel->mipi_device), (u8[]) {0x0A} , 1, &data, sizeof(data) );
rc = mipi_dsi_dcs_read(&(display->panel->mipi_device), (u8) 0x0A, &data2, 1); //MIPI_DCS_GET_POWER_MODE
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(2)发现在dsi_ctrl_cmd_transfer中有用cmd_flags DSI_CTRL_CMD_READ区分读写操作，高通的接口中dsi_display_read_status有设

dsi_host_transfer   
	if(*(u8 *)msg->tx_buf == 0x0A){
		cmd_flags |= DSI_CTRL_CMD_READ | DSI_CTRL_CMD_CUSTOM_DMA_SCHED | DSI_CTRL_CMD_FETCH_MEMORY ;
	}
	dsi_ctrl_cmd_transfer
所以在dsi_ctrl_cmd_transfer函数前传入带DSI_CTRL_CMD_READ的cmd_flags
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(3)两个接口返回的值出现不同，在dsi_message_rx中进行分析

mipi_dsi_generic_read
 返回的packet 0x11 0x9D 0x9D 0x1B    MIPI_DSI_RX_GENERIC_SHORT_READ_RESPONSE_1BYTE	= 0x11,
mipi_dsi_dcs_read
 返回的packet 0x0A 0x9D 0xEB 0x40    data[0] 是返回的响应，这里会返回一个error无法解析到0x9D
dsi_display_read_status  
 返回的packet 0x1C 0x03 0x00 0x16 0x9D 0x9D  MIPI_DSI_RX_DCS_LONG_READ_RESPONSE		= 0x1c,
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data[0] 是返回的响应 ,mipi_dsi_dcs_read返回的响应值0x0A，没有对应的响应，与mipi_dsi_generic_read相比就msg->type不同(将mipi_dsi_dcs_read的msg->type与mipi_dsi_generic_read保持一致，现象同mipi_dsi_generic_read一致没问题，可以正常读取)；与dsi_display_read_status(rx_len = 3 FAE提供的 qcom,mdss-dsi-panel-status-read-length )相比就rx_len不同，虽然说都能读到0x9D，无法解析，将dsi_display_read_status (rx_len = 1) 也会出现mipi_dsi_dcs_read的现象，esd返回值有问题导致一直闪屏, 后续换了不同IC厂商的屏幕，调用接口未发现上述的问题，就这个屏调用mipi_dsi_dcs_read返回的data[0]一直是0x0A。

Qualcomm

Set Settings

(1)parse dtsi
    mdss_panel_parse_dt -> mdss_panel_parse_display_timings -> mdss_dsi_panel_config_res_properties
        mdss_dsi_parse_dcs_cmds(np, &pt->on_cmds, "qcom,mdss-dsi-on-command",

(2)map cmd type to dtsi and packet
    dsi_panel_parse_cmd_sets -> dsi_panel_parse_cmd_sets_sub -> dsi_panel_create_cmd_packets ↓↓↓
	
	dsi_cmd_set_type ——    cmd_set_prop_map  
     DSI_CMD_SET_ON    "qcom,mdss-dsi-on-command"

(3)set settings
    dsi_panel_enable type = DSI_CMD_SET_ON 
        dsi_panel_tx_cmd_set —— dsi_host_transfer —— dsi_ctrl_cmd_transfer 

以qcom,mdss-dsi-on-command第一组setting为例子
    39 01 00 00 00 00 04 B9 FF 83 99
	cmd.msg.type = data[0] = DCS Long Write   39 cmd type
	cmd.last_command = (data[1] == 1)         01 flags  MIPI_DSI_MSG_LASTCOMMAND 区分独立包
	cmd.msg.channel = data[2];                00 dsi_panel_drv_init channel = 0
	cmd.msg.flag | = data[3];                 00 flags MIPI_DSI_MSG_USE_LPM LP Mode传输
	cmd.post.wait_ms = data[4];               00 delay time
	cmd.msg.tx_len = (data[5]<<8 | data[6])   04 payload size
    
    for (j = 0; j < cmd[i].msg.tx_len; j++)
       payload[j] = data[7 + j];	          B9 FF 83 99 payload data
	cmd[i].msg.tx_buf = payload;
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ESD Check FLow

plane的更新只发生在crtc enable被启动的过程，所以在sde_crtc_enable中调度workqueue,

sde_crtc_enable                                                                 
    sde_connector_schedule_status_work(cstate->connectors[i], true);      
        schedule_delayed_work(&c_conn->status_work, msecs_to_jiffies(interval));   
        sde_connector_check_status_work  
            dsi_display_check_status 
              dsi_display_status_reg_read    
                 dsi_display_validate_status       
                    dsi_display_read_status  
                    dsi_display_validate_reg_read     

其中注意
dsi_display_read_status  —— dsi_ctrl_cmd_transfer     (payload transfer flow) 

中断处理esd的问题，检测到状态不对后执行soft_reset进行复位
dsi_ctrl_isr  ddevm_request_threaded_irq
    dsi_ctrl_handle_error_status
   		dsi_ctrl->hw.ops.soft_reset(&dsi_ctrl->hw);
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这个一般还是需要原厂进行支持，需要注意的就是格式个数对应，以免esd check的流程中出现问题

devicetree
qcom,esd-check-enabled;
qcom,mdss-dsi-panel-status-check-mode="reg_read";
qcom,mdss-dsi-panel-status-command = [
                06 01 00 01 05 00 01 09
                06 01 00 01 05 00 01 68];
qcom,mdss-dsi-panel-status-command-state = "dsi_lp_mode";
qcom,mdss-dsi-panel-status-value = <0x80 0x73 0x04>, <0xC0>;
qcom,mdss-dsi-panel-status-read-length = <3 1>;
qcom,mdss-dsi-panel-max-error-count = <2>;
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