[PATCH v11 20/24] arm64: dts: rockchip: enable vop2 and hdmi tx on rock-3a

[Piotr Oniszczuk]

> Wiadomość napisana przez Robin Murphy <robin.murphy at arm.com> w dniu 11.07.2022, o godz. 12:41:
> 
> On 2022-06-25 16:31, Piotr Oniszczuk wrote:
>>> Wiadomość napisana przez Peter Geis <pgwipeout at gmail.com> w dniu 25.06.2022, o godz. 16:00:
>>> 
>>> 
>>> The first issue you have is the TV isn't responding until the absolute
>>> end.
>> I suspect this is because lack on idle gaps between cec commands sent from board to tv.
>> Maybe TV sw. can't deal with consecutive commands without any idle between them?
>> It is interesting that disconnecting TV - so CEC line is driven only by board - rock3a still don't have any idle gaps while rock3b (and radxa 4.19 bsp) has them (very similar between 5.18mailine and 4.19 bsp).
>> How this is possible that change I/O from m0->m1 impacts _timings_ on free hanging CEC line?
> 
> Check all the pinctrl settings beyond just the function mux - pulls, drive strength, output type, etc. - the defaults tend to be all over the place, and rarely what you want.
> 
> Robin.

Robin,

I'm not sure do I looked in right place...

but:

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/arm64/boot/dts/rockchip/rk3568-pinctrl.dtsi?h=v5.18.10#n788

vs.

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/arm64/boot/dts/rockchip/rk3568-pinctrl.dtsi?h=v5.18.10#n795

are looking ok?


> 
>>> This strikes me as a signal integrity issue. Do you have an
>>> oscilloscope (not a logic analyzer, you need voltages and ramp times)
>>> to compare the working vs non-working signals? Check both sides of the
>>> level shifter.
>> Indeed - i will verify this with digital oscilloscope.
>> Already ordered and must await week or 2 for delivery :-(
>> My analog oscilloscope shows correct levels and slopes "seems" to be the same like in working (no memory so i can compare only visually on fuzzy screen)
>> For me key is to understand why on rock3a there is no any idles between cec commands - even when nothing is connected to bard (so cec is only sending and nothing external impacts cec state machine)....
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