Re: [PATCHv15 3/7] video: add of helper for display timings/videomode

[Tomi Valkeinen <tomi.valkeinen-l0cyMroinI0@public.gmane.org>]

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On 2012-12-07 16:12, Philipp Zabel wrote:
> Hi,
> 
> Am Montag, den 26.11.2012, 18:56 +0200 schrieb Tomi Valkeinen:

>> So what does the pixelclk-inverted mean? Normally the SoC drives pixel
>> data on rising edge, and the panel samples it at falling edge? And
>> vice-versa for inverted? Or the other way around?
>>
>> When is hsync/vsync set? On rising or falling edge of pclk?
>>
>> My point here is that the pixelclk-inverted is not crystal clear thing,
>> like the hsync/vsync/de-active values are.
>>
>> And while thinking about this, I realized that the meaning of
>> pixelclk-inverted depends on what component is it applied to. Presuming
>> normal pixclk means "pixel data on rising edge", the meaning of that
>> depends on do we consider the SoC or the panel. The panel needs to
>> sample the data on the other edge from the one the SoC uses to drive the
>> data.
>>
>> Does the videomode describe the panel, or does it describe the settings
>> programmed to the SoC?
> 
> How about calling this property pixelclk-active, active high meaning
> driving pixel data on rising edges and sampling on falling edges (the
> pixel clock is high between driving and sampling the data), and active
> low meaning driving on falling edges and sampling on rising edges?
> It is the same from the SoC perspective and from the panel perspective,
> and it mirrors the usage of the other *-active properties.

This sounds good to me. It's not quite correct, as neither pixelclock or
pixel data are not really "active" when the clock is high/low, but it
still makes sense and is clear (at least with a short description).

 Tomi



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