windows-xp/Source/XPSP1/NT/drivers/video/ms/cirrus/mini/clddc2b.c

/*++

Copyright (c) 1996  Microsoft Corporation

Module Name:

    clddc2b.c

Abstract:
    
    This module checks for a DDC monitor, and returns the 
    established Timings value from the EDID if found.

Environment:

    Kernel mode only

Notes:

Revision History:

  * plc3  10-23-95  VESA DDC2B support.
  *
  * sge01 09-25-96  Non DDC Moniotr table support
  *
  * sge02 10-14-96  Detailed timing calculation in EDID
  *
  * sge03 12-05-96  Only check active pixel clock in detailed timing.
  *
--*/
//---------------------------------------------------------------------------
                                                       
#include <dderror.h>
#include <devioctl.h>                           
#include <miniport.h>
                                                        
#include <ntddvdeo.h>                        
#include <video.h>
#include "cirrus.h"

#define ERROR              0

#define OFF                0
#define ON                 1

#define SDA_BIT            2
#define SCL_BIT            1
#define SCL_BIT_ON         1
#define SCL_BIT_OFF        0

#define DELAY_COUNT            255

UCHAR WaitCount ;
UCHAR Err ;

VOID ReadVESATiming(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   

VOID EnableDDC(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
BOOLEAN IsDDC2(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
VOID DisableDDC(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
VOID StartDDC(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
VOID StopDDC(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
VOID ProcessDDC2(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );     
                                               
BOOLEAN ReadSDA(
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
BOOLEAN ReadSCL(
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
BOOLEAN ReadBit(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );

BOOLEAN ReadByte(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );
                                                    
VOID SetSCL(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension,
    UCHAR status
    );
                                                   
VOID SetData(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
BOOLEAN SetClock(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );
                                                    
VOID WaitVerticalRetrace(
    PHW_DEVICE_EXTENSION HwDeviceExtension,
    UCHAR count
    );                                                   

VOID WaitDelay(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
VOID ClearData(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
BOOLEAN SendByte(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension,
    UCHAR data
    );                                                   

BOOLEAN SendDDCCommand(                        
    PHW_DEVICE_EXTENSION HwDeviceExtension
    );                                                   
 
BOOLEAN
CheckDDC2BMonitor(
    PHW_DEVICE_EXTENSION HwDeviceExtension,
    ULONG i
    );

ULONG
CalculateMaxinumTiming(
    );

VOID ProcessNonDDC(
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    );

VP_STATUS
CirrusNonDDCRegistryCallback(
    PVOID HwDeviceExtension,
    PVOID Context,
    PWSTR ValueName,
    PVOID ValueData,
    ULONG ValueLength
    );

#if defined(ALLOC_PRAGMA)               
#pragma alloc_text (PAGE,ReadVESATiming)
#pragma alloc_text (PAGE,EnableDDC)
#pragma alloc_text (PAGE,IsDDC2)
#pragma alloc_text (PAGE,DisableDDC)
#pragma alloc_text (PAGE,StartDDC)
#pragma alloc_text (PAGE,StopDDC)
#pragma alloc_text (PAGE,ProcessDDC2)
#pragma alloc_text (PAGE,ReadSDA)
#pragma alloc_text (PAGE,ReadSCL)
#pragma alloc_text (PAGE,ReadBit)
#pragma alloc_text (PAGE,ReadByte)
#pragma alloc_text (PAGE,SetSCL)
#pragma alloc_text (PAGE,SetData)
#pragma alloc_text (PAGE,SetClock)
#pragma alloc_text (PAGE,WaitVerticalRetrace)
#pragma alloc_text (PAGE,WaitDelay)
#pragma alloc_text (PAGE,ClearData)
#pragma alloc_text (PAGE,SendByte)
#pragma alloc_text (PAGE,SendDDCCommand)
#pragma alloc_text (PAGE,CheckDDC2BMonitor)
#pragma alloc_text (PAGE,CalculateMaxinumTiming)
#pragma alloc_text (PAGE,ProcessNonDDC)
#pragma alloc_text (PAGE,CirrusNonDDCRegistryCallback)
#endif                                               

UCHAR EDIDBuffer[128] ;
UCHAR EDIDTiming_I    ;
UCHAR EDIDTiming_II   ;
UCHAR EDIDTiming_III  ;
UCHAR DDC2BFlag       ;
UCHAR NonDDCTable     ;
ULONG ulEDIDMaxTiming ;

UCHAR SDAValue ;

/*-------------------------------------------------------------------------*/
VOID EnableDDC (
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    UCHAR ReadSR08      ;
    UCHAR WaitCount = 2 ;

    VideoDebugPrint((1, "CLDDC2B!EnableDDC\n"));

    VideoPortWritePortUchar (HwDeviceExtension->IOAddress + SEQ_ADDRESS_PORT,
                                 0x08) ;

    ReadSR08 = VideoPortReadPortUchar (HwDeviceExtension->IOAddress +
                                           SEQ_DATA_PORT) ;
    // Enable DDC2B Configuration 
    ReadSR08 |= 0x43 ;

    VideoPortWritePortUchar (HwDeviceExtension->IOAddress + SEQ_DATA_PORT,
                                 ReadSR08) ;

    WaitVerticalRetrace (HwDeviceExtension, WaitCount) ;
    
} /*-----  EnableDDC  -----*/ 


/*-------------------------------------------------------------------------*/
VOID DisableDDC (
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    UCHAR ReadSEQADDR, ReadSEQDATA ;
    UCHAR DDCStatus ;

    VideoDebugPrint((1, "CLDDC2B!DisableDDC\n"));

    if ((DDCStatus = SendDDCCommand ( HwDeviceExtension )) == 1)
        goto DDC_ERROR ;

    // i 3c5 ReadSEQDATA 
    ReadSEQDATA = VideoPortReadPortUchar ( HwDeviceExtension->IOAddress + 
                                              SEQ_DATA_PORT ) ;
    // Disable DDC2B Configuration 
    ReadSEQDATA &= 0xBC ;

    // o 3c5 ReadSEQDATA
    VideoPortWritePortUchar ( HwDeviceExtension->IOAddress + SEQ_DATA_PORT,
                                 ReadSEQDATA ) ;

DDC_ERROR:
    return ;

}  /*-------  DisableDDC  -------*/ 


/*-------------------------------------------------------------------------*/
VOID ProcessDDC2 (
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{                      
    UCHAR DDCStatus, i ;
    UCHAR checksum, header ;

    VideoDebugPrint((1, "CLDDC2B!ProcessDDC2\n"));

    DDC2BFlag = 0 ;

    if ((DDCStatus = SendDDCCommand ( HwDeviceExtension )) == 1) {
        VideoDebugPrint((0, "CLDDC2B!ProcessDDC2: Infinite wait state ...\n"));
        goto PROCESSDDC_EXIT ;
    }

    for (i = 0; i < 128; i++) {
        EDIDBuffer[i] = ReadByte (HwDeviceExtension) ;
	if (Err) {
            VideoDebugPrint((0, "CLDDC2B!ProcessDDC2: Infinite wait state ...\n"));
            goto PROCESSDDC_EXIT ;
        }
    }

    //
    // Check EDID table 8-byte header
    // The correct first 8 bytes of EDID table is 0x00, 0xFF, 0xFF, 0xFF, 
    //                                            0xFF, 0xFF, 0xFF, 0x00
    //

    if ((EDIDBuffer[0] != 0) ||
        (EDIDBuffer[7] != 0)) {
        VideoDebugPrint((1, "CLDDC2B: Invalid EDID header table\n"));
        StopDDC (HwDeviceExtension) ;
        return ;
    }
    for (i = 1; i < 7; i++) {
         if (EDIDBuffer[i] != 0xFF) {
            VideoDebugPrint((1, "CLDDC2B: Invalid EDID header table\n"));
            StopDDC (HwDeviceExtension) ;
            return ;
        }
    }

    //
    // Calculate checksum of 128-byte EDID table.
    // 
    checksum = 0x00 ;

    for (i = 0; i < 128; i++) {
        checksum += EDIDBuffer[i] ;
    }

    VideoDebugPrint((1, "CLDDC2B: EDID Table check sum = %d\n", checksum));

    //
    // EDID table checksum must be zero.
    // 
    if (checksum) {
        VideoDebugPrint((1, "CLDDC2B: Invalid checksum of EDID table\n"));
    }
    else
    {
        //
        // Set DDC2B Flag and find timing values.
        // 
        DDC2BFlag      = 1 ;
        EDIDTiming_I   = EDIDBuffer[35] ; 
        EDIDTiming_II  = EDIDBuffer[36] ;
        EDIDTiming_III = EDIDBuffer[37] ;
        ulEDIDMaxTiming= CalculateMaxinumTiming();
        VideoDebugPrint((1, "CLDDC2B: DDC2B is supported\n"));
    }

PROCESSDDC_EXIT:
    StopDDC (HwDeviceExtension) ;
    return ;

}  /*-------  ProcessDDC2  -------*/ 


/*-------------------------------------------------------------------------*/
VOID StartDDC (
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{

    VideoDebugPrint((1, "DDC2B!StartDDC\n"));

    SetSCL (HwDeviceExtension, ON)  ;
    ClearData (HwDeviceExtension) ;
    SetSCL (HwDeviceExtension, OFF) ;

}  /*-------  StartDDC  -------*/ 


/*-------------------------------------------------------------------------*/
VOID StopDDC (
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{

    VideoDebugPrint((1, "DDC2B!StopDDC\n"));

    SetSCL (HwDeviceExtension, ON) ;
    SetData (HwDeviceExtension) ;

}  /*-------  StopDDC  -------*/ 


/*-------------------------------------------------------------------------*/
BOOLEAN ReadSCL (
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    UCHAR ReadSEQDATA, status ;

    // i 3c5 ReadSEQDATA 
    ReadSEQDATA = VideoPortReadPortUchar ( HwDeviceExtension->IOAddress + 
                                              SEQ_DATA_PORT ) ;

    // Read SR08.B2
    ReadSEQDATA = ( (ReadSEQDATA) & 0x04 ) >> 2 ;

    return (ReadSEQDATA) ;

}  /*-------  ReadSCL  -------*/ 


/*-------------------------------------------------------------------------*/
VOID SetSCL(                        
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension,
    UCHAR status
    )
{
    UCHAR ReadSEQADDR, ReadSEQDATA ;

    // i 3c5 ReadSEQDATA 
    ReadSEQDATA = VideoPortReadPortUchar (HwDeviceExtension->IOAddress + 
                                              SEQ_DATA_PORT) ;

    ReadSEQDATA = ( ( ReadSEQDATA & 0xFE ) | status ) ;

    // o 3c5 ReadSEQDATA
    VideoPortWritePortUchar (HwDeviceExtension->IOAddress + SEQ_DATA_PORT,
                                 ReadSEQDATA) ;

    WaitDelay (HwDeviceExtension) ; 

}  /*-------  SetSCL  -------*/ 


/*-------------------------------------------------------------------------*/
BOOLEAN ReadSDA (
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    UCHAR ReadSEQADDR, ReadSEQDATA ;

    // i 3c5 ReadSEQDATA 
    ReadSEQDATA = VideoPortReadPortUchar (HwDeviceExtension->IOAddress + 
                                              SEQ_DATA_PORT) ;

    ReadSEQDATA = ( ReadSEQDATA & 0x80 ) >> 7 ;

    return ( ReadSEQDATA ) ;

}  /*-------  ReadSDA  -------*/ 


/*-------------------------------------------------------------------------*/
VOID ClearData
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    UCHAR ReadSEQADDR, ReadSEQDATA ;


    // i 3c5 ReadSEQDATA 
    ReadSEQDATA = VideoPortReadPortUchar (HwDeviceExtension->IOAddress + 
                                              SEQ_DATA_PORT) ;

    ReadSEQDATA &= 0xFD ;

    // o 3c5 ReadSEQDATA
    VideoPortWritePortUchar (HwDeviceExtension->IOAddress + SEQ_DATA_PORT,
                                 ReadSEQDATA) ;

    WaitDelay (HwDeviceExtension) ; 

}  /*-------  ClearData  -------*/ 


/*-------------------------------------------------------------------------*/
VOID SetData 
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    UCHAR ReadSEQADDR, ReadSEQDATA ;

    // i 3c5 ReadSEQDATA 
    ReadSEQDATA = VideoPortReadPortUchar (HwDeviceExtension->IOAddress + 
                                              SEQ_DATA_PORT) ;

    ReadSEQDATA |= 0x02 ;

    // o 3c5 ReadSEQDATA
    VideoPortWritePortUchar (HwDeviceExtension->IOAddress + SEQ_DATA_PORT,
                                 ReadSEQDATA) ;

    WaitDelay (HwDeviceExtension) ; 

}  /*-------  SetData  -------*/ 


/*-------------------------------------------------------------------------*/
BOOLEAN SetClock 
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    ULONG i ;
    UCHAR status ;

    SetSCL (HwDeviceExtension, ON) ;

    for (i = 0; i < DELAY_COUNT; i++)
        status = ReadSCL (HwDeviceExtension) ;

    SetSCL (HwDeviceExtension, OFF) ;

    if (!status)
        VideoDebugPrint((0, "DDC2B!SetClock: Infinite wait state ...\n"));
    
    if (status == 1)
        return ( FALSE ) ; // retuern 0 -> OK
    else 
        return ( TRUE ) ;  // retuern 1 -> Infinite wait state
                         

}  /*-------  SetClock  -------*/ 


/*-------------------------------------------------------------------------*/
BOOLEAN ReadBit 
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    USHORT i ; 
    UCHAR  bit ;

    SetSCL (HwDeviceExtension, ON) ;
    for (i = 0; i < DELAY_COUNT; i++)
        ReadSCL (HwDeviceExtension) ;

    bit = ReadSDA (HwDeviceExtension) ;

    SetSCL (HwDeviceExtension, OFF) ;
   
    return ( bit ) ;

}  /*-------  ReadBit  -------*/ 


/*-------------------------------------------------------------------------*/
BOOLEAN ReadByte 
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension
    )
{

    UCHAR ReadByteValue, bit, i ;

    SetData ( HwDeviceExtension ) ;

    ReadByteValue = 0 ;

    for (i = 0; i < 8; i++) {
        ReadByteValue <<= 1  ;
        bit = ReadBit ( HwDeviceExtension ) ;
        ReadByteValue |= bit ;
    }

    if ((bit & 0x02) != 0) {
        SetData ( HwDeviceExtension ) ;
    } else {
        ClearData ( HwDeviceExtension ) ;
    }

    SetClock ( HwDeviceExtension ) ;

     SetData ( HwDeviceExtension ) ;

    return (ReadByteValue) ;

} /*-----  ReadByte  -----*/ 


/*-------------------------------------------------------------------------*/
BOOLEAN SendByte ( 
/*-------------------------------------------------------------------------*/
    PHW_DEVICE_EXTENSION HwDeviceExtension,
    UCHAR data
    )
{
    UCHAR i ;

    UCHAR Mask[8] = { 0x80, 0x40, 0x20, 0x10, 
                      0x08, 0x04, 0x02, 0x01 } ; 

    for (i = 0; i < 8; i++)
    {
        if (data & Mask[i]) {
            SetData ( HwDeviceExtension ) ;
        } else { 
            ClearData ( HwDeviceExtension ) ;
        }
	Err = SetClock ( HwDeviceExtension ) ;
    }

    if (Err) {
        SetSCL ( HwDeviceExtension, OFF )  ;
        ClearData (HwDeviceExtension) ;
    } else {
        SetData ( HwDeviceExtension ) ;
        SetSCL ( HwDeviceExtension, ON )  ;
        ReadBit ( HwDeviceExtension ) ;  // Discard acknowledge bit
    }

    return (Err) ;

}  /*-------  SendByte  -------*/ 


/*-------------------------------------------------------------------------*/
BOOLEAN IsDDC2
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension
    )
{
    UCHAR DDCStatus, SCLStatus ;

    VideoDebugPrint((1, "DDC2B!IsDDC2\n"));

    SetSCL (HwDeviceExtension, OFF) ;
    SCLStatus = ReadSCL(HwDeviceExtension) ;
    if (SCLStatus != 0) {
        return ( FALSE ) ;
    }

    SetSCL (HwDeviceExtension, ON) ;
    SCLStatus = ReadSCL (HwDeviceExtension) ;
    if (SCLStatus != 1) {
        return ( FALSE ) ;
    } 

    return ( TRUE ) ; 

}  /*-------  IsDDC2  -------*/ 


/*-------------------------------------------------------------------------*/
BOOLEAN SendDDCCommand
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    UCHAR ClockStatus ;

    VideoDebugPrint((1, "DDC2B!SendDDCCommand\n"));

    StartDDC ( HwDeviceExtension ) ;

    ClockStatus = SendByte ( HwDeviceExtension, 0xA0 ) ;
    if (ClockStatus)
        VideoDebugPrint((0, "DDC2B!SendDDCCommand: Infinite wait state ...\n"));
 
    ClockStatus = SendByte ( HwDeviceExtension, 0x00 ) ;
    if (ClockStatus)
        VideoDebugPrint((0, "DDC2B!SendDDCCommand: Infinite wait state ...\n"));

    StopDDC  ( HwDeviceExtension ) ;


    StartDDC ( HwDeviceExtension ) ;

    ClockStatus = SendByte ( HwDeviceExtension, 0xA1 ) ;
    if (ClockStatus)
        VideoDebugPrint((0, "DDC2B!SendDDCCommand: Infinite wait state ...\n"));

    SetData  ( HwDeviceExtension ) ;

    return (ClockStatus) ;  

}  /*-------  SendDDCCommand  -------*/ 


/*-------------------------------------------------------------------------*/
VOID WaitDelay 
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{
    PUCHAR InStatPort ;

    //
    // Set up port addresses for color/mono
    //
    if (VideoPortReadPortUchar (HwDeviceExtension->IOAddress +
                                    MISC_OUTPUT_REG_READ_PORT) & 0x01) {
        InStatPort = HwDeviceExtension->IOAddress + INPUT_STATUS_1_COLOR ;
    } else {
        InStatPort = HwDeviceExtension->IOAddress + INPUT_STATUS_1_MONO ;
    }

    while ((VideoPortReadPortUchar (InStatPort) & 0x01) != 0) ;
    while ((VideoPortReadPortUchar (InStatPort) & 0x01) == 0) ;
    while ((VideoPortReadPortUchar (InStatPort) & 0x01) != 0) ;

}  /*-------  wait_delay  -------*/ 


/*-------------------------------------------------------------------------*/
VOID WaitVerticalRetrace
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension,
    UCHAR waitcount
    )
{ 
    PUCHAR InStatPort ;
    ULONG i ;
    
    //
    // Set up port addresses for color/mono
    //
    if (VideoPortReadPortUchar (HwDeviceExtension->IOAddress +
                                    MISC_OUTPUT_REG_READ_PORT) & 0x01) {
        InStatPort = INPUT_STATUS_1_COLOR + HwDeviceExtension->IOAddress;
    } else {
        InStatPort = INPUT_STATUS_1_MONO + HwDeviceExtension->IOAddress;
    }
        
    for (i = 0; i < waitcount; i++) 
    {
        while ((VideoPortReadPortUchar (InStatPort) & 0x08) != 0) ;
        while ((VideoPortReadPortUchar (InStatPort) & 0x08) == 0) ;
    }  

}  /*-------  WaitVerticalRetrace  -------*/

    

/*-------------------------------------------------------------------------*/
VOID ReadVESATiming
/*-------------------------------------------------------------------------*/
    (
    PHW_DEVICE_EXTENSION HwDeviceExtension
    )
{
    UCHAR status ; 

    VideoDebugPrint((1, "DDC2B!ReadVESATiming\n"));
#if 1 // NonDDC #sge
    //
    // clear flag.
    //
    NonDDCTable = 0;
    DDC2BFlag   = 0;
#endif
    EnableDDC (HwDeviceExtension) ;

    if ((status = IsDDC2 (HwDeviceExtension)) != 0x00) {
        ProcessDDC2 (HwDeviceExtension) ;
    }
#if 1 // NonDDC #sge
    if(!DDC2BFlag)
        ProcessNonDDC(HwDeviceExtension);
#endif

    DisableDDC (HwDeviceExtension) ;

    return ;

}  /*-----  ReadVESATiming  -----*/

BOOLEAN
CheckDDC2BMonitor(
    PHW_DEVICE_EXTENSION HwDeviceExtension,
    ULONG i
    )

/*++

Routine Description:
    Determines if refresh rate support according to DDC2B standard.

Arguments:
    HwDeviceExtension - Pointer to the miniport driver's device extension.

Return Value:
    None.

--*/
{

    ULONG ulCurrTiming ;
#if 1 // NonDDC #sge
    if (!DDC2BFlag && !NonDDCTable)
        return TRUE ;
#else
    if (!DDC2BFlag)
        return TRUE ;
#endif

    VideoDebugPrint((4, "CheckDDC2B\n"));
    VideoDebugPrint((4, "refresh rate   = %ld\n", ModesVGA[i].Frequency));
    VideoDebugPrint((4, "hres           = %d\n", ModesVGA[i].hres));
    VideoDebugPrint((4, "vres           = %d\n", ModesVGA[i].vres));

    ulCurrTiming = ModesVGA[i].Frequency *
                   ModesVGA[i].hres *
                   ModesVGA[i].vres ;

    VideoDebugPrint((4, "ulCurrTiming = %d\n", ulCurrTiming)) ;

    VideoDebugPrint((4, "ulEDIDMaxTiming = %d\n", ulEDIDMaxTiming)) ;

    if ( ulCurrTiming > ulEDIDMaxTiming ) 
        return FALSE ;
    else
        return TRUE ;

}  // end of CheckDDC2bMonitor


ULONG
CalculateMaxinumTiming(
    )

/*++

Routine Description:
    Determines maximum allowablt VESA timing value.

Arguments:
    None.

Return Value:
    None.

--*/
{

    ULONG    current_timing_value ;
    ULONG    freq ;
    SHORT    i ;
    USHORT    usHzActive, usHzBlanking, usVtActive, usVtBlanking;
    ULONG    maximum_allowable_timing_value = ulEDIDMaxTiming;

    VideoDebugPrint((1, "CLDDC2B: CalculateMaxinumTiming\n")) ;

    //
    // Calculate established timing values
    // 
    /* 720 * 400 * 70 = 20160000 */
    if ( EDIDTiming_I & 0x80 ) {
        VideoDebugPrint((1, "CLDDC2B: 720 * 400 * 70\n")) ;
        if (maximum_allowable_timing_value < ((ULONG) 20160000)) {
            maximum_allowable_timing_value = ((ULONG) 20160000) ;
        }
    }

    /* 720 * 400 * 88 = 25344000 */
    if ( EDIDTiming_I & 0x40 ) {
        VideoDebugPrint((1, "CLDDC2B: 720 * 400 * 88\n")) ;
        if (maximum_allowable_timing_value < ((ULONG) 25344000)) {
            maximum_allowable_timing_value = ((ULONG) 25344000) ;
        }
    }

    /* 640 * 480 * 60 = 18432000 */
    if ( EDIDTiming_I & 0x20 ) {
        VideoDebugPrint((1, "CLDDC2B: 640 * 480 * 60\n"));
        if (maximum_allowable_timing_value < ((ULONG) 18432000)) {
            maximum_allowable_timing_value = ((ULONG) 18432000) ;
        }
    }

    /* 640 * 480 * 67 = 20582400 */
    if ( EDIDTiming_I & 0x10 ) {
        VideoDebugPrint((1, "CLDDC2B: 640 * 480 * 67\n"));
        if (maximum_allowable_timing_value < ((ULONG) 20582400)) {
            maximum_allowable_timing_value = ((ULONG) 20582400) ;
        }
    }
         
    /* 640 * 480 * 72 = 22118400 */
    if ( EDIDTiming_I & 0x08 ) {
        VideoDebugPrint((1, "CLDDC2B: 640 * 480 * 72\n"));
        if (maximum_allowable_timing_value < ((ULONG) 22118400)) {
            maximum_allowable_timing_value = ((ULONG) 22118400) ;
        }
    }

    /* 640 * 480 * 75 = 23040000 */
    if ( EDIDTiming_I & 0x04 ) {
        VideoDebugPrint((1, "CLDDC2B: 640 * 480 * 75\n"));
        if (maximum_allowable_timing_value < ((ULONG) 23040000)) {
            maximum_allowable_timing_value = ((ULONG) 23040000) ;
        }
    }

    /* 800 * 600 * 56 = 26880000 */
    if ( EDIDTiming_I & 0x02 ) {
        VideoDebugPrint((1, "CLDDC2B: 800 * 600 * 56\n"));
        if (maximum_allowable_timing_value < ((ULONG) 26880000)) {
            maximum_allowable_timing_value = ((ULONG) 26880000) ;
        }
    }

    /* 800 * 600 * 60 = 28800000 */
    if ( EDIDTiming_I & 0x01 ) {
        VideoDebugPrint((1, "CLDDC2B: 800 * 600 * 60\n"));
        if (maximum_allowable_timing_value < ((ULONG) 28800000)) {
            maximum_allowable_timing_value = ((ULONG) 28800000) ;
        }
    }   

    /* 800 * 600 * 72 = 34560000 */
    if ( EDIDTiming_II & 0x80 ) {
        VideoDebugPrint((1, "CLDDC2B: 800 * 600 * 72\n"));
        if (maximum_allowable_timing_value < ((ULONG) 34560000)) {
            maximum_allowable_timing_value = ((ULONG) 34560000) ;
        } 
    }

    /* 800 * 600 * 75 = 36000000 */
    if ( EDIDTiming_II & 0x40 ) {
        VideoDebugPrint((1, "CLDDC2B: 800 * 600 * 75\n"));
        if (maximum_allowable_timing_value < ((ULONG) 36000000)) {
            maximum_allowable_timing_value = ((ULONG) 36000000) ; 
        }
    }

    /* 832 * 624 * 75 = 38937600 */
    if ( EDIDTiming_II & 0x20 ) {
        VideoDebugPrint((1, "CLDDC2B: 832 * 624 * 75\n"));
        if (maximum_allowable_timing_value < ((ULONG) 38937600)) {
            maximum_allowable_timing_value = ((ULONG) 38937600) ; 
        }
    }

    /* 1024 * 768 * 43 = 33816576 */
    if ( EDIDTiming_II & 0x10 ) {
        VideoDebugPrint((1, "CLDDC2B: 1024 * 768 * 43\n"));
        if (maximum_allowable_timing_value < ((ULONG) 33816576)) {
            maximum_allowable_timing_value = ((ULONG) 33816576) ;
        }
    }

    /* 1024 * 768 * 60 = 47185920 */
    if ( EDIDTiming_II & 0x08 ) {
        VideoDebugPrint((1, "CLDDC2B: 1024 * 768 * 60\n"));
        if (maximum_allowable_timing_value < ((ULONG) 47185920)) {
            maximum_allowable_timing_value = ((ULONG) 47185920) ;
        }
    }

    /* 1024 * 768 * 70 = 55050240 */
    if ( EDIDTiming_II & 0x04 ) {
        VideoDebugPrint((1, "CLDDC2B: 1024 * 768 * 70\n"));
        if (maximum_allowable_timing_value < ((ULONG) 55050240)) {
            maximum_allowable_timing_value = ((ULONG) 55050240) ;
        }
    }

    /* 1024 * 768 * 75 = 58982400 */
    if ( EDIDTiming_II & 0x02 ) {
        VideoDebugPrint((1, "CLDDC2B: 1024 * 768 * 75\n"));
        if (maximum_allowable_timing_value < ((ULONG) 58982400)) {
            maximum_allowable_timing_value = ((ULONG) 58982400) ;
        }
    }

    /* 1280 * 1024 * 75 = 98304000 */
    if ( EDIDTiming_II & 0x01 ) {
        VideoDebugPrint((1, "CLDDC2B: 1280 * 1024 * 75\n"));
        if (maximum_allowable_timing_value < ((ULONG) 98304000)) {
            maximum_allowable_timing_value = ((ULONG) 98304000) ;
        }
    }

    /* 1152 * 870 * 75 = 75168000 */
    if ( EDIDTiming_III & 0x80 ) {
        VideoDebugPrint((1, "CLDDC2B: 1152 * 870 * 75\n"));
        if (maximum_allowable_timing_value < ((ULONG) 75168000)) {
            maximum_allowable_timing_value = ((ULONG) 75168000) ;
        }
    }

    //
    // Calculate standard timing values
    // 

    for ( i = 0x26 ; i <= 0x35 ; i+=2 ) {
        current_timing_value = 0L ;
        freq = ( EDIDBuffer[i+1] & 0x3F ) + 60 ;
        switch ( EDIDBuffer[i] ) {
            case 0x31 :                                 // 640 * 480 = 307200 
                current_timing_value = ((ULONG) freq) * 307200 ;
                VideoDebugPrint((1, "CLDDC2B: 640 * 480 * %d\n", freq));
                break ;   
            case 0x3B :                                 // 720 * 400 = 288000
                current_timing_value = ((ULONG) freq) * 288000 ;
                VideoDebugPrint((1, "CLDDC2B: 640 * 480 * %d\n", freq));
                break ;   
            case 0x45 :                                 // 800 * 600 = 480000
                current_timing_value = ((ULONG) freq) * 480000 ;
                VideoDebugPrint((1, "CLDDC2B: 800 * 600 * %d\n", freq));
                break ;   
            case 0x61 :                                // 1024 * 768 = 786432
                current_timing_value = ((ULONG) freq) * 786432 ;
                VideoDebugPrint((1, "CLDDC2B: 1024 * 768 * %d\n", freq));
                break ;   
            case 0x71 :                               // 1152 * 870 = 1002240
                current_timing_value = ((ULONG) freq) * 1002240 ;
                VideoDebugPrint((1, "CLDDC2B: 1152 * 870 * %d\n", freq));
                break ;   
            case 0x81 :                              // 1280 * 1024 = 1310720
                current_timing_value = ((ULONG) freq) * 1310720 ;
                VideoDebugPrint((1, "CLDDC2B: 1280 * 1024 * %d\n", freq));
                break ;   
            case 0xA9 :                              // 1600 * 1200 = 1920000
                current_timing_value = ((ULONG) freq) * 1920000 ;
                VideoDebugPrint((1, "CLDDC2B: 1600 * 1200 * %d\n", freq));
                break ;   
            default :
                ;
        }

        if (maximum_allowable_timing_value < current_timing_value) 
            maximum_allowable_timing_value = current_timing_value ;

    }

// sge02
    //
    // Calculate detailed timing values
    // 

    for ( i = 0x36 ; i <= 0x7D; i+=18 ) 
    {
        current_timing_value = EDIDBuffer[i] ;
        current_timing_value += EDIDBuffer[i+1] * 256;
        //
        // Validation.
        //
        // sge03
        if (current_timing_value <= 0x0101 )
            continue;
        current_timing_value *= 10000;
        //
        // Calculate Horizontal Active and Blanking
        //
        usHzActive    = (EDIDBuffer[i+4] & 0xf0);
        usHzActive    <<= 4;
        usHzActive    |= EDIDBuffer[i+2];
        usHzBlanking = (EDIDBuffer[i+4] & 0x0f);
        usHzBlanking <<= 8;
        usHzBlanking |= EDIDBuffer[i+3];
        //
        // Calculate Vertical Active and Blanking
        //
        usVtActive    = (EDIDBuffer[i+7] & 0xf0);
        usVtActive    <<= 4;
        usVtActive    |= EDIDBuffer[i+5];
        usVtBlanking = (EDIDBuffer[i+7] & 0x0f);
        usVtBlanking <<= 8;
        usVtBlanking |= EDIDBuffer[i+6];

        current_timing_value = (current_timing_value + usHzActive + usHzBlanking - 1) / (usHzActive + usHzBlanking);
        current_timing_value = (current_timing_value + usVtActive + usVtBlanking - 1) / (usVtActive + usVtBlanking);
        current_timing_value *= usHzActive; 
        current_timing_value *= usVtActive; 

        if (maximum_allowable_timing_value < current_timing_value) 
            maximum_allowable_timing_value = current_timing_value ;

    }

    return (maximum_allowable_timing_value);

}  // end of CalculateMaxinumTiming 

//---------------------------------------------------------------------------
//
// Function:
//     Read NonDDC Table from Registry and Set NonDDCTable Flag.
//
// Input:
//     HwDeviceExtension - Pointer to the miniport driver's device extension.         
//
// Output: 
//     None
//
//---------------------------------------------------------------------------
VOID ProcessNonDDC(
    PHW_DEVICE_EXTENSION HwDeviceExtension 
    )
{                      
    ULONG i ;

    VideoDebugPrint((1, "NonDDC!ProcessNonDDC\n"));

    NonDDCTable = 0 ;

    if (NO_ERROR == VideoPortGetRegistryParameters(HwDeviceExtension,
                                                   L"NonDDCMonitor.Data",
                                                   FALSE,
                                                   CirrusNonDDCRegistryCallback,
                                                   NULL)) 
    {
        // 
        // We got the table 
        //
        //
        // Check EDID table 8-byte header
        // The correct first 8 bytes of EDID table is 0x00, 0xFF, 0xFF, 0xFF, 
        //                                            0xFF, 0xFF, 0xFF, 0x00
        //

        if ((EDIDBuffer[0] != 0) ||
            (EDIDBuffer[7] != 0)) 
        {
            VideoDebugPrint((1, "CLNonDDC: Invalid EDID header table\n"));
            return ;
        }
        for (i = 1; i < 7; i++) 
        {
            if (EDIDBuffer[i] != 0xFF) 
            {
                VideoDebugPrint((1, "CLNonDDC: Invalid EDID header table\n"));
                return ;
            }
        }

        //
        // Set NonDDCTable Flag and find timing values.
        // 
        NonDDCTable    = 1 ;
        EDIDTiming_I   = EDIDBuffer[35] ; 
        EDIDTiming_II  = EDIDBuffer[36] ;
        EDIDTiming_III = EDIDBuffer[37] ;
        ulEDIDMaxTiming= CalculateMaxinumTiming();
        VideoDebugPrint((1, "NonDDC: NonDDC is supported\n"));
    }
} // end of ProcessNonDDC