[linux-sunxi] Re: [RFC PATCH 01/11] dt-bindings: update the binding for Allwinner H3 TVE support

[wens@csie.org (Chen-Yu Tsai)]

On Sat, May 20, 2017 at 2:06 AM, Icenowy Zheng <icenowy@aosc.io> wrote:
>
>
> ? 2017?5?20? GMT+08:00 ??2:02:15, Maxime Ripard <maxime.ripard@free-electrons.com> ??:
>>On Thu, May 18, 2017 at 12:43:44AM +0800, Icenowy Zheng wrote:
>>> -On SoCs other than the A33 and V3s, there is one more clock
>>required:
>>> +For the following compatibles:
>>> +   * allwinner,sun5i-a13-tcon
>>> +   * allwinner,sun6i-a31-tcon
>>> +   * allwinner,sun6i-a31s-tcon
>>> +   * allwinner,sun8i-a33-tcon
>>> +   * allwinner,sun8i-v3s-tcon
>>> +there is one more clock and one more property required:
>>> + - clocks:
>>> +   - 'tcon-ch0': The clock driving the TCON channel 0
>>> + - clock-output-names: Name of the pixel clock created
>>> +
>>> +For the following compatibles:
>>> +   * allwinner,sun5i-a13-tcon
>>> +   * allwinner,sun6i-a31-tcon
>>> +   * allwinner,sun6i-a31s-tcon
>>> +   * allwinner,sun8i-h3-tcon0
>>> +there is one more clock required:
>>>     - 'tcon-ch1': The clock driving the TCON channel 1
>>
>>Putting ID's in the compatible name is usually a bad idea. What is the
>>difference between the two? Only that the second one doesn't have a
>>clock?
>
> Yes.
>
>>
>>That seems highly unlikely. How does it generate the pixel clock
>>frequency?
>
> Yes it seems impossible, but it's also the fact.
>
> There's only one CLK_TCON in H3/5, which is for TCON0.
>
> It's possible that lcd-ch1 clk is CLK_TVE, but it's still a weird situation --
> Although we have a lcd-ch1 clock, we cannot touch it, otherwise
> the TVE will refuse to work (the TVE can only work under 216MHz).

Assuming the TV encoder is like the old one, then it never had a
separate module clock. Instead its timing signals are fed from the
TCON. So CLK_TVE is likely the clock for TCON1 here.

ChenYu