HDMI

Overview

HDMI

High-definition multimedia interface (HDMI) is an interface for transmitting audio and video data from a source device, such as a DVD player or set-top box (STB), to a sink device, such as a TV or display.

Basic Concepts

HDMI is an audio and video transmission protocol released by Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, and Toshiba. The transmission process complies with the Transition Minimized Differential Signaling (TMDS) protocol.

TMDS is used to transmit audio, video, and various auxiliary data.
Display data channel (DDC) allows the TX and RX ends to obtain the sending and receiving capabilities. However, the HDMI only needs to unidirectionally obtain the capabilities of the RX end (display).
Consumer Electronics Control (CEC) enables interaction between the HDMI TX and RX devices.
Fixed rate link (FRL) allows the maximum TMDS bandwidth to be increased from 18 Gbit/s to 48 Gbit/s.
High-bandwidth Digital Content Protection (HDCP) prevents copying of digital audio and video content being transmitted across devices.

Working Principles

In the HDF, the HDMI module uses the independent service mode for API adaptation. In this mode, each device independently publishes a device service to process external access requests. After receiving an access request, the device manager extracts the parameters in the request to call the internal method of the target device. In the independent service mode, the service management capabilities of the HDFDeviceManager can be directly used. However, you need to configure a node for each device, which increases the memory usage.

Figure 1 Independent service mode

Constraints

Currently, the HDMI module supports only the kernels (LiteOS) of mini and small systems.

Development Guidelines

Use Cases

HDMI features high transmission rate, wide transmission bandwidth, high compatibility, and can transmit uncompressed audio and video signals. Compared with the traditional full analog interface, HDMI simplifies connection between devices and provides HDMI-specific intelligent features, which are ideal for high-quality audio and video transmission of small-sized devices.

Available APIs

HdmiCntlrOps:

struct HdmiCntlrOps {
    void (*hardWareInit)(struct HdmiCntlr *cntlr);
    void (*hardWareStatusGet)(struct HdmiCntlr *cntlr, struct HdmiHardwareStatus *status);
    void (*controllerReset)(struct HdmiCntlr *cntlr);
    bool (*hotPlugStateGet)(struct HdmiCntlr *cntlr);
    bool (*hotPlugInterruptStateGet)(struct HdmiCntlr *cntlr);
    void (*lowPowerSet)(struct HdmiCntlr *cntlr, bool enable);
    void (*tmdsModeSet)(struct HdmiCntlr *cntlr, enum HdmiTmdsModeType mode);
    int32_t (*tmdsConfigSet)(struct HdmiCntlr *cntlr, struct HdmiTmdsConfig mode);
    void (*infoFrameEnable)(struct HdmiCntlr *cntlr, enum HdmiPacketType infoFrameType, bool enable);
    int32_t (*infoFrameSend)(struct HdmiCntlr *cntlr, enum HdmiPacketType infoFrameType, uint8_t *data, uint32_t len);
    int32_t (*infoFrameDataSet)(struct HdmiCntlr *cntlr, uint32_t type, uint8_t *data, uint32_t len);
    int32_t (*cecMsgSend)(struct HdmiCntlr *cntlr, struct HdmiCecMsg *msg);
    void (*audioPathEnable)(struct HdmiCntlr *cntlr, bool enable);
    void (*audioPathSet)(struct HdmiCntlr *cntlr, struct HdmiAudioConfigInfo *config);
    void (*phyOutputEnable)(struct HdmiCntlr *cntlr, bool enable);
    void (*phyOutputSet)(struct HdmiCntlr *cntlr, struct HdmiPhyCfg *cfg);
    void (*blackDataSet)(struct HdmiCntlr *cntlr, bool enable);
    void (*videoMuteEnable)(struct HdmiCntlr *cntlr, bool enable);
    void (*videoPathSet)(struct HdmiCntlr *cntlr, struct HdmiVideoAttr *attr);
    void (*audioMuteEnable)(struct HdmiCntlr *cntlr, bool enable);
    void (*avmuteSet)(struct HdmiCntlr *cntlr, bool enable);
    int32_t (*ddcTransfer)(struct HdmiCntlr *cntlr, struct HdmiDdcCfg *ddcCfg);
    bool (*scdcSourceScrambleGet)(struct HdmiCntlr *cntlr);
    int32_t (*scdcSourceScrambleSet)(struct HdmiCntlr *cntlr, bool enable);
    void (*frlSet)(struct HdmiCntlr *cntlr);
    int32_t (*frlEnable)(struct HdmiCntlr *cntlr, bool enable);
    int32_t (*audioNctsSet)(struct HdmiCntlr *cntlr, struct HdmiFrlAudioNctsConfig *cfg);
    void (*frlTrainingConfigSet)(struct HdmiCntlr *cntlr, struct HdmiFrlTrainConfig *cfg);
    void (*frlTrainingStart)(struct HdmiCntlr *cntlr);
    void (*frlGetTriningRslt)(struct HdmiCntlr *cntlr, struct HdmiFrlTrainRslt *rslt);
    void (*hdcpRegInit)(struct HdmiCntlr *cntlr);
    int32_t (*hdcpGenerateAksvAndAn)(struct HdmiCntlr *cntlr);
    int32_t (*hdcpOptReg)(struct HdmiCntlr *cntlr, enum HdmiHdcpRegOptType type, uint8_t *data, uint32_t len);
    void (*hdrTimerSet)(struct HdmiCntlr *cntlr, struct HdmiHdrTimerConfig *config);
};

Table 1 Description of the HdmiCntlrOps structure

Function	Input Parameter	Output Parameter	Return Value	Description
hardWareInit	cntlr: structure pointer to an HDMI controller at the core layer.	–	–	Initializes the HDMI hardware.
hardWareStatusGet	cntlr: structure pointer to an HDMI controller at the core layer.	status: pointer to the HDMI hardware status.	–	Obtains the HDMI hardware status.
controllerReset	cntlr: structure pointer to an HDMI controller at the core layer.	–	–	Resets an HDMI controller.
hotPlugStateGet	cntlr: structure pointer to an HDMI controller at the core layer.	–	bool: HDMI hot-plug status.	Obtains the HDMI hot-plug status.
hotPlugInterruptStateGet	cntlr: structure pointer to an HDMI controller at the core layer.	–	bool: HDMI hot-plug interrupt status.	Obtains the HDMI hot-plug interrupt status.
lowPowerSet	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable low power consumption.	–	–	Enables or disables low power consumption.
tmdsModeSet	cntlr: structure pointer to an HDMI controller at the core layer. mode: TMDS mode.	–	–	Sets the TMDS mode.
tmdsConfigSet	cntlr: structure pointer to an HDMI controller at the core layer. mode: TMDS parameters.	–	HDF_STATUS	Sets TMDS parameters.
infoFrameEnable	cntlr: structure pointer to an HDMI controller at the core layer. infoFrameType: packet type. enable: whether to enable infoFrame.	–	–	Enables or disables infoFrame.
infoFrameSend	cntlr: structure pointer to an HDMI controller at the core layer. infoFrameType: packet type. data: pointer to infoFrame data. len: data length.	–	HDF_STATUS	Sends an infoFrame.
cecMsgSend	cntlr: structure pointer to an HDMI controller at the core layer. msg: pointer to the CEC message	–	HDF_STATUS	Sends a CEC message.
audioPathEnable	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable the audio path.	–	–	Enables or disables the audio path.
audioPathSet	cntlr: structure pointer to an HDMI controller at the core layer. config: pointer to the audio path configuration.	–	–	Sets the audio path.
phyOutputEnable	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable the physical layer output.	–	–	Enables or disables the physical layer output.
phyOutputSet	cntlr: structure pointer to an HDMI controller at the core layer. cfg: pointer to the physical layer configuration.	–	–	Sets the physical layer information.
blackDataSet	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable the black screen.	–	–	Sets the black screen.
videoMuteEnable	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable the video mute feature.	–	–	Enables or disables the video mute feature.
videoPathSet	cntlr: structure pointer to an HDMI controller at the core layer. attr: pointer to the video path configuration.	–	–	Sets the video path.
audioMuteEnable	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable the audio mute feature.	–	–	Enables or disables the audio mute feature.
avmuteSet	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable the AV mute feature.	–	–	Enables or disables the AV mute feature.
ddcTransfer	cntlr: structure pointer to an HDMI controller at the core layer. ddcCfg: pointer to the DDC configuration.	ddcCfg: DDC configuration.	HDF_STATUS	Reads and writes data through the DDC.
scdcSourceScrambleGet	cntlr: structure pointer to an HDMI controller at the core layer.	–	Scrambling status of the source.	Obtains the scrambling status of the source.
scdcSourceScrambleSet	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable the scrambling for the source.	–	HDF_STATUS	Enables or disable scrambling for the source.
frlEnable	cntlr: structure pointer to an HDMI controller at the core layer. enable: whether to enable the FRL.	–	HDF_STATUS	Enables or disables the FRL.
audioNctsSet	cntlr: structure pointer to an HDMI controller at the core layer. cfg: pointer to the N/CTS configuration.	–	HDF_STATUS	Sets the audio N/CTS information.
frlTrainingConfigSet	cntlr: structure pointer to an HDMI controller at the core layer. cfg: pointer to the FRL training configuration.	–	–	Sets FRL training information.
frlTrainingStart	cntlr: structure pointer to an HDMI controller at the core layer.	–	–	Starts FRL training.
frlGetTriningRslt	cntlr: structure pointer to an HDMI controller at the core layer.	rslt: FRL training result.	–	Obtains the FRL training result.
hdcpRegInit	cntlr: structure pointer to an HDMI controller at the core layer.	–	–	Initializes registers related to the High-bandwidth Digital Content Protection (HDCP) process.
hdcpGenerateAksvAndAn	cntlr: structure pointer to an HDMI controller at the core layer.	–	HDF_STATUS	Generates the Aksv and An in the HDCP process.
hdcpOptReg	cntlr: structure pointer to an HDMI controller at the core layer. type: operation type. data: register data. len: data length.	data: register data.	HDF_STATUS	Reads or writes the registers during the HDCP process.
hdrTimerSet	cntlr: structure pointer to an HDMI controller at the core layer. config: pointer to the timer configuration	–	–	Sets the HDR-related timer.

How to Develop

The HDMI module adaptation involves the following steps:

Instantiate the driver entry.
- Instantiate the HdfDriverEntry structure.
- Call HDF_INIT to register the HdfDriverEntry instance with the HDF.
Configure attribute files.
- Add the deviceNode information to the device_info.hcs file.
- (Optional) Add the hdmi_config.hcs file.
Instantiate the HDMI controller object.
- Initialize HdmiCntlr.
- Instantiate HdmiCntlrOps in HdmiCntlr.

Instantiate the driver entry.

The driver entry must be a global variable of the HdfDriverEntry type (which is defined in hdf_device_desc.h), and the value of moduleName must be the same as that in device_info.hcs. In the HDF, the start address of each HdfDriverEntry object of all loaded drivers is collected to form a segment address space similar to an array for the upper layer to invoke.

Generally, the HDF calls the Bind() function and then the Init() function to load a driver. If Init() fails to be called, the HDF calls Release() to release driver resources and exit.

HDMI driver entry reference:
```
struct HdfDriverEntry g_hdmiDriverEntry = {
    .moduleVersion = 1,
    .Bind = HdmiAdapterBind,
    .Init = HdmiAdapterInit,
    .Release = HdmiAdapterRelease,
    .moduleName = "adapter_hdmi_driver",// (mandatory) The value must be the same as that in the .hcs file.
};
HDF_INIT(g_hdmiDriverEntry);            // Call HDF_INIT to register the driver entry with the HDF.
```

Configure attribute files.

Add deviceNode to the device_info.hcs file, and configure the device attributes in the hdmi_config.hcs file. The deviceNode information is related to registration of the driver entry. The device attribute values are closely related to the driver implementation and the default values or restriction ranges of the HdmiCntlr members at the core layer.

Configure HDMI controller information from the first node. This node specifies a type of HDMI controllers rather than a specific HDMI controller. In this example, there is only one HDMI controller. If there are multiple HDMI controllers, you need to add the deviceNode information to the device_info file and add the corresponding device attributes to the hdmi_config file.

device_info.hcs configuration reference

root {
    platform :: host {
         device_hdmi :: device {
            device0 :: deviceNode {
                policy = 2;         // The value 2 means to publish a service.
                priority = 20;     // Driver startup priority.
                permission = 0644; // Permission to create device nodes for the driver.
                serviceName = "HDF_PLATFORM_HDMI_0"; // (Mandatory) Unique name of the service published by the driver.
                moduleName = "hdmi_driver";         // (Mandatory) Driver name, which must be the same as moduleName in the driver entry.
                deviceMatchAttr = "adapter_hdmi_driver"; // (Mandatory) Controller private data, which must be same as that of the corresponding controller in hdmi_config.hcs.
            }                                             // The specific controller information is in hdmi_config.hcs.
         }
    }
}

hdmi_config.hcs configuration reference

 root {
     platform {
        hdmi_config {
            template hdmi_controller {    // Template configuration. In the template, you can configure the common parameters shared by device nodes.
                match_attr = "";            // (Mandatory) The value must be the same as that of deviceMatchAttr in device_info.hcs.
                index = 0;                 // (Mandatory) HDMI controller number.
                regBasePhy = 0x10100000; // (Mandatory) Physical base address of the register.
                regSize = 0xd1;            // (Mandatory) Register bit width.
                irqNum = 100;            //(Mandatory) Interrupt request (IRQ) number.
                maxTmdsClock = 300;
                videoTiming = 10;
                quantization = 1;
                colorSpace = 0;
                colorimetry = 0;
                audioIfType = 0;
                audioBitDepth = 1;
                audioSampleRate = 2;
                audioChannels = 1;
                hdrColorimetry = 4;
                hdrUserMode = 1;
                cap = 0xd001e045;
            }
            controller_0x10100000 :: hdmi_controller {
                match_attr = "adapter_hdmi_driver";
                index = 0;
                regBasePhy = 0x10100000;
                irqNum = 100;
                maxTmdsClock = 400;
                defTmdsClock = 300;
                maxFrlRate = 600;
                videoTiming = 10;
                quantization = 1;
                colorSpace = 0;
                colorimetry = 0;
                audioIfType = 0;
                audioSampleRate = 2;
                audioChannels = 1;
                hdrColorimetry = 4;
                hdrUserMode = 1;
                cap = 0xd001e045;
            }
        }
    }
}

Instantiate the HdmiCntlr object.

Initialize the HdmiCntlr object at the core layer, including initializing the vendor custom structure (passing parameters and data) and instantiating the HdmiCntlrOps (used to call the underlying functions of the driver). The HdfDriverEntry member functions (Bind, Init, and Release) must be implemented in this step.

Custom structure reference

NOTE
To the driver, the custom structure carries parameters and data. The values in the hdmi_config.hcs file are read by the HDF, and structure members are initialized by DeviceResourceIface. Some important values (such as the device number and bus number) are also passed to the HdmiCntlr object at the core layer.

struct HdmiAdapterHost {
    struct HdmiCntlr *cntlr;        // (Mandatory) Control object at the core layer. The details are as follows:
    volatile unsigned char *regBase;// (Mandatory) Register base address.
    uint32_t regBasePhy            // (Mandatory) Physical base address of the register.
    uint32_t regSize;               // (Mandatory) Register bit width.
    uint32_t irqNum;                // (Mandatory) IRQ number.
};

/* HdmiCntlr is the controller structure at the core layer. Its members are assigned with values by using the Init() function. */
struct HdmiCntlr {
    struct IDeviceIoService service;
    struct HdfDeviceObject *hdfDevObj;
    struct PlatformDevice device;
    struct OsalMutex mutex;
    struct PlatformQueue *msgQueue;
    struct HdmiCntlrCap cap;
    struct HdmiAttr attr;
    struct HdmiCntlrOps *ops;
    uint32_t deviceIndex;
    uint32_t state;                 // Controller status.
    enum HdmiTmdsModeType tmdsMode;
    struct HdmiDevice *hdmi;
    struct HdmiInfoframe infoframe;
    struct HdmiScdc *scdc;
    struct HdmiDdc ddc;
    struct HdmiFrl *frl;
    struct HdmiHdcp *hdcp;
    struct HdmiCec *cec;
    struct HdmiEvent event;
    struct HdmiHdr *hdr;
    void *priv;
};

Instantiate HdmiCntlrOps in HdmiCntlr.

static struct HdmiCntlrOps g_hdmiAdapterHostOps = {
    .hardWareInit = HdmiAdapterHardWareInit,
    .hardWareStatusGet = HdmiAdapterHardWareStatusGet,
    .controllerReset = HdmiAdapterControllerReset,
    .hotPlugStateGet = HdmiAdapterHotPlugStateGet,
    .hotPlugInterruptStateGet = HdmiAdapterHotPlugInterruptStateGet,
    .lowPowerSet = HdmiAdapterLowPowerSet,
    .tmdsModeSet = HdmiAdapterTmdsModeSet,
    .tmdsConfigSet = HdmiAdapterTmdsConfigSet,
    .infoframeEnable = HdmiAdapterInfoframeEnable,
    .infoframeSend = HdmiAdapterInfoframeSend,
    .infoframeDataSet = HdmiAdapterInfoframeDataSet,
    .cecMsgSend = HdmiAdapterCecMsgSend,
    .audioPathEnable = HdmiAdapterAudioPathEnable,
    .audioPathSet = HdmiAdapterAudioPathSet,
    .phyOutputEnable = HdmiAdapterPhyOutputEnable,
    .phyOutputSet = HdmiAdapterPhyOutputSet,
    .blackDataSet = HdmiAdapterBlackDataSet,
    .videoMuteEnable = HdmiAdapterVideoMuteEnable,
    .videoPathSet = HdmiAdapterVideoPathSet,
    .audioMuteEnable = HdmiAdapterAudioMuteEnable,
    .avmuteSet = HdmiAdapterAvmuteSet,
    .ddcTransfer = HdmiAdapterDdcTransfer,
    .scdcSourceScrambleGet = HdmiAdapterScdcSourceScrambleGet,
    .scdcSourceScrambleSet = HdmiAdapterScdcSourceScrambleSet,
    .frlSet = HdmiAdapterFrlSet,
    .frlEnable = HdmiAdapterFrlEnable,
    .audioNctsSet = HdmiAdapterAudioNctsSet,
    .frlTrainingConfigSet = HdmiAdapterFrlTrainingConfigSet,
    .frlTrainingStart = HdmiAdapterFrlTrainingStart,
    .frlGetTriningRslt = HdmiAdapterFrlGetTriningRslt,
    .hdcpRegInit = HdmiAdapterHdcpRegInit,
    .hdcpGenerateAksvAndAn = HdmiAdapterHdcpGenerateAksvAndAn,
    .hdcpOptReg = HdmiAdapterHdcpOptReg,
    .hdrTimerSet = HdmiAdapterHdrTimerSet,
};

Bind() function

Input parameter: HdfDeviceObject, an interface parameter exposed by the driver, contains the .hcs configuration.

Return value: HDF_STATUS (The following table lists some states. For more details, see HDF_STATUS definition in the /drivers/framework/include/utils/hdf_base.h file.)

State	Description
HDF_ERR_INVALID_OBJECT	Invalid controller object.
HDF_ERR_INVALID_PARAM	Invalid parameter.
HDF_ERR_MALLOC_FAIL	Memory allocation failed.
HDF_ERR_IO	I/O error.
HDF_SUCCESS	Transmission successful.
HDF_FAILURE	Transmission failed.

    **Function description**:
    Initializes the custom structure object **HdmiAdapterHost** and **HdmiCntlr**, and calls the **HdmiCntlrAdd** function to add the HDMI controller to the core layer.
    
    The **HdmiCntlr**, **HdmiAdapterHost**, and **HdfDeviceObject** assign values with each other so that other functions can be converted successfully.

    ```c
    static int32_t HdmiAdapterBind(struct HdfDeviceObject *obj)
    {
        struct HdmiCntlr *cntlr = NULL;
        struct HimciAdapterHost *host = NULL;
        int32_t ret;
        cntlr = (struct HdmiCntlr *)OsalMemCalloc(sizeof(struct HdmiCntlr));
        if (cntlr == NULL) {
            HDF_LOGE("%s: malloc cntlr failed!", __func__);
            return HDF_ERR_MALLOC_FAIL;
        }
        host = (struct HimciAdapterHost *)OsalMemCalloc(sizeof(struct HimciAdapterHost));
        if (host == NULL) {
            HDF_LOGE("%s: malloc host failed!", __func__);
            return HDF_ERR_MALLOC_FAIL;
        }
        cntlr->priv = (void *)host;     // (Mandatory) Store host to the private data of cntlr.
        cntlr->ops = &g_hdmiHostOps;     // (Mandatory) Connect to the HdmiCntlrOps instance.
        cntlr->hdfDevObj = obj;          // (Mandatory) Prerequisites for conversion between HdfDeviceObject and HdmiCntlr.
        obj->service = &cntlr->service; // (Mandatory) Prerequisites for conversion between HdfDeviceObject and HdmiCntlr.
        ret = HdmiAdapterCntlrParse(cntlr, obj); // (Mandatory) Initialize cntlr. If the operation fails, execute goto__ERR.
        ... 
        ret = HdmiAdapterHostParse(host, obj); // (Mandatory) Initialize the attributes of the host object. If the initialization fails, execute goto__ERR.
        ...
        ret = HdmiAdapterHostInit(host, cntlr);  // Perform vendor custom structure initialization. If the initialization fails, execute goto __ERR.
        ...
        ret = HdmiCntlrAdd(cntlr);              // Call the function at the core layer. If the operation fails, execute goto__ERR.
        ...
        HDF_LOGD("HdmiAdapterBind: success.");
        return HDF_SUCCESS;
    __ERR:
        HdmiAdapterDeleteHost(host);
        HDF_LOGD("HdmiAdapterBind: fail, err = %d.", ret);
        return ret;
    }
    ```

- **Init()** function

    **Input parameter**:
    **HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs configuration.
    
    **Return value**:
    HDF_STATUS
    
    **Function description**:
    
    Implements the **HdmiAdapterInit** function.

    ```c
    static int32_t HdmiAdapterInit(struct HdfDeviceObject *obj)
    {
        return HDF_SUCCESS;
    }
    ```

- **Release()** function

    **Input parameter**:
    **HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs configuration.
   
    **Return value**:
    –
    
    **Function description**:
    Releases the memory and deletes the controller. This function assigns a value to the **Release()** API in the driver entry structure. If the HDF fails to call the **Init()** function to initialize the driver, the **Release()** function can be called to release driver resources.

    ```c
    static void HdmiAdapterRelease(struct HdfDeviceObject *obj)
    {
        struct HdmiCntlr *cntlr = NULL;
        ...
        cntlr = (struct MmcCntlr *)obj->service;// Forcibly convert HdfDeviceObject to HdmiCntlr by using service. For details about the value assignment, see the Bind() function.
        ...
        HimciDeleteHost((struct HimciAdapterHost *)cntlr->priv);// Memory release function customized by the vendor. A forced conversion from HdmiCntlr to HimciAdapterHost is involved in the process.
    }
    ```
    
    > ![](../public_sys-resources/icon-note.gif) **NOTE**<br/>
    > All forced conversion operations for obtaining the corresponding object can be successful only when the **Init()** function has the corresponding value assignment operations.