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Date:   Tue, 09 Nov 2021 20:36:06 +0000
From:   Paul Cercueil <paul@crapouillou.net>
Subject: Re: [PATCH v5 5/7] MIPS: DTS: jz4780: Account for Synopsys HDMI
 driver and LCD controllers
To:     "H. Nikolaus Schaller" <hns@goldelico.com>
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Hi Nikolaus,

Le mar., nov. 9 2021 at 21:19:17 +0100, H. Nikolaus Schaller 
<hns@goldelico.com> a ?crit :
> Hi Paul,
> 
>>  Am 07.11.2021 um 20:05 schrieb Paul Cercueil <paul@crapouillou.net>:
>> 
>>>  6. Therefore I think it *may* work overclocked with 48MHz
>>>  but is not guaranteed or reliable above 27 MHz.
>>>  So everything is ok here.
>> 
>>  One thing though - the "assigned-clocks" and 
>> "assigned-clock-rates", while it works here, should be moved to the 
>> CGU node, to respect the YAML schemas.
> 
> Trying to do this seems to break boot.
> 
> I can boot up to
> 
> [    8.312926] dw-hdmi-ingenic 10180000.hdmi: registered DesignWare 
> HDMI I2C bus driver
> 
> and
> 
> [   11.366899] [drm] Initialized ingenic-drm 1.1.0 20200716 for 
> 13050000.lcdc0 on minor 0
> 
> but then the boot process becomes slow and hangs. Last sign of 
> activity is
> 
> [   19.347659] hub 1-0:1.0: USB hub found
> [   19.353478] hub 1-0:1.0: 1 port detected
> [   32.321760] wlan0_power: disabling
> 
> What I did was to just move
> 
> 		assigned-clocks = <&cgu JZ4780_CLK_HDMI>;
> 		assigned-clock-rates = <27000000>;
> 
> from
> 
> 	hdmi: hdmi@10180000 {
> 
> to
> 
> 	cgu: jz4780-cgu@10000000 {
> 
> Does this mean the clock is assigned too early or too late?
> 
> Do you have any suggestions since I don't know the details of CGU.

These properties are already set for the CGU node in ci20.dts:

&cgu {
	/*
	 * Use the 32.768 kHz oscillator as the parent of the RTC for a higher
	 * precision.
	 */
	assigned-clocks = <&cgu JZ4780_CLK_OTGPHY>, <&cgu JZ4780_CLK_RTC>;
	assigned-clock-parents = <0>, <&cgu JZ4780_CLK_RTCLK>;
	assigned-clock-rates = <48000000>;
};

So you want to update these properties to add the HDMI clock setting, 
like this:

	assigned-clocks = <&cgu JZ4780_CLK_OTGPHY>, <&cgu JZ4780_CLK_RTC>, 
<&cgu JZ4780_CLK_HDMI>;
	assigned-clock-parents = <0>, <&cgu JZ4780_CLK_RTCLK>;
	assigned-clock-rates = <48000000>, <0>, <27000000>;

Cheers,
-Paul