LCD的像素时钟

1. pixclock - pixel clock in pico seconds ；

2. First, calculate the required pixclock rate. XFree86 uses megahertz whilst framebuffer devices uses picoseconds (Why, I don't know)；

3.The speed at which the electron beam paints the pixels is determined by the dotclock in the graphics board. For a dotclock of e.g. 28.37516 MHz (millions of cycles per second), each pixel is 35242 ps (picoseconds) long:
    1/(28.37516E6 Hz) = 35.242E-9 s

从上面这三段话可以看出，VCLK和pixclock只不过是像素时钟的两种描述：一个是像素时钟的频率，一个是像素时钟的周期。一个表示我一秒钟可以写多少个像素，单位MHz。一个表示我写一个像素需要多少时间，单位ps（1.0E-12s）。