[Spca50x-devs] Query about delays of 2ms in spca5xx-20060402 driver

[<srivas.ramgopal@xxxxxxxxx>]

Hi,
 
I am using a Phillips SPC200NC webcam on a PCMCIA-card.  I am facing a
very peculiar problem.  Following are the steps I performed.

1. I connect the webcam to my card, without the spca5xx client driver
loaded.
2. I loaded the spca5xx driver.
3. Started streaming using spcaview.  Streaming is successful.
4. I unloaded the driver and reloaded the driver.
5. Started streaming using spcaview.  Streaming doesn't happen.

On investigation of the spca5xx driver code, I found the following:

1. When the driver is loaded, the function "zcxx_probeSensor" is
called, and there are several register read and write operations
performed.

2. In the above-mentioned function, there were three 2ms
delay statements, which were commented.

3. When I uncommented these delay statements, this problem was resolved.

Following is the code snippett of the function zc3xx_probeSensor:

static int zcxx_probeSensor(struct usb_spca50x *spca50x)
{
    int i, j;
    __u8 retbyte = 0;
    __u16 checkword = 0;
   __u16 checkid = 0xffff;
/* check i2c */
/* check SIF */
    for (i = 0; i < SIFTOT; i++) {
	spca5xxRegWrite(spca50x->dev, 0xa0, 0x01, 0x0000, NULL, 0);
	spca5xxRegWrite(spca50x->dev, 0xa0,
zcxxi2cSensorSIF[i][SensorId],
			0x0010, NULL, 0);
	spca5xxRegWrite(spca50x->dev, 0xa0, 0x01, 0x0001, NULL, 0);
	spca5xxRegWrite(spca50x->dev, 0xa0, 0x03, 0x0012, NULL, 0);
	spca5xxRegWrite(spca50x->dev, 0xa0, 0x01, 0x0012, NULL, 0);
	//wait_ms(2);
	if (zcxxi2cSensorSIF[i][reg8d] == 0x8d)
	    spca5xxRegWrite(spca50x->dev, 0xa0,
zcxxi2cSensorSIF[i][val8d],
			    0x008d, NULL, 0);
	wait_ms(150);
	retbyte =
	    zcxx_i2cWrite(spca50x->dev, zcxxi2cSensorSIF[i][SensorReg1],
			  zcxxi2cSensorSIF[i][valSreg1L],
			  zcxxi2cSensorSIF[i][valSreg1H]);
	//wait_ms(2);
	retbyte =
	    (zcxx_i2cRead(spca50x->dev,
zcxxi2cSensorSIF[i][SensorReg1])) &
	    0xff;
	//wait_ms(2);

Can someone explain the significance of these delay statements and why
they were commented?

Regards,
Srivas

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