Re: [PATCH v4 4/4] arm64: dts: rk3399-pinephone-pro: Add internal display support

From: Javier Martinez Canillas <javierm@redhat.com>
To: "Ondřej Jirman" <megi@xff.cz>,
	linux-kernel@vger.kernel.org,
	"Kamil Trzciński" <ayufan@ayufan.eu>,
	"Martijn Braam" <martijn@brixit.nl>,
	"Sam Ravnborg" <sam@ravnborg.org>,
	"Robert Mader" <robert.mader@posteo.de>,
	"Tom Fitzhenry" <tom@tom-fitzhenry.me.uk>,
	"Peter Robinson" <pbrobinson@gmail.com>,
	"Onuralp Sezer" <thunderbirdtr@fedoraproject.org>,
	dri-devel@lists.freedesktop.org,
	"Maya Matuszczyk" <maccraft123mc@gmail.com>,
	"Neal Gompa" <ngompa13@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	"Krzysztof Kozlowski" <krzysztof.kozlowski@linaro.org>,
	"Jagan Teki" <jagan@amarulasolutions.com>,
	"Caleb Connolly" <kc@postmarketos.org>,
	"Heiko Stuebner" <heiko@sntech.de>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	devicetree@vger.kernel.org, linux-rockchip@lists.infradead.org
Subject: Re: [PATCH v4 4/4] arm64: dts: rk3399-pinephone-pro: Add internal display support
Date: Sat, 31 Dec 2022 16:29:49 +0100	[thread overview]
Message-ID: <e21b5c12-0cc0-5ec0-b2c6-9dde633d5e10@redhat.com> (raw)
In-Reply-To: <20221230153745.tfs6n4zy4xfwugbw@core>

Hello Ondřej,

Thanks a lot for your feedback.

On 12/30/22 16:37, Ondřej Jirman wrote:

[...]

>>  &i2c0 {
>>  	clock-frequency = <400000>;
>>  	i2c-scl-rising-time-ns = <168>;
>> @@ -214,6 +251,9 @@ vcc3v0_touch: LDO_REG2 {
>>  				regulator-name = "vcc3v0_touch";
>>  				regulator-min-microvolt = <3000000>;
>>  				regulator-max-microvolt = <3000000>;
>> +				regulator-state-mem {
>> +					regulator-off-in-suspend;
>> +				};
> 
> You're instructing RK818 to shut down the regulator for touch controller during
> suspend, but I think Goodix driver expects touch controller to be kept powered on
> during suspend. Am I missing something?
> 
> https://elixir.bootlin.com/linux/latest/source/drivers/input/touchscreen/goodix.c#L1405
>

You tell me, it is your patch :) I just cherry-picked this from your tree:

https://github.com/megous/linux/commit/11f8da60d6a5

But if that is not correct, then I can drop the regulator-off-in-suspend.

[...]

>> +
>> +	touchscreen@14 {
>> +		compatible = "goodix,gt917s";
> 
> This is not the correct compatible. Pinephone Pro uses Goodix GT1158:
> 
> Goodix-TS 3-0014: ID 1158, version: 0100
> Goodix-TS 3-0014: Direct firmware load for goodix_1158_cfg.bin failed with error -2
> 
>

Same thing. I wasn't aware of this since your patch was using this compatible
string. If "goodix,gt1158" is the correct compatible string, then I agree we
should have that instead even when the firmware is missing. Because the DT is
supposed to describe the hardware. The FW issue can be tackled as a follow-up.

[...] 

>> +
>> +&vopb {
>> +	status = "okay";
>> +	assigned-clocks = <&cru DCLK_VOP0_DIV>, <&cru DCLK_VOP0>,
>> +			  <&cru ACLK_VOP0>, <&cru HCLK_VOP0>;
>> +	assigned-clock-rates = <0>, <0>, <400000000>, <100000000>;
>> +	assigned-clock-parents = <&cru PLL_CPLL>, <&cru DCLK_VOP0_FRAC>;
>> +};
> 
> So here you're putting a fractional clock into path between CPLL -> VOP0_DIV
> -> DCLK_VOP0_FRAC -> DCLK_VOP0.
> 
> Fractional clocks require 20x difference between input and output rates, and
> CPLL is 800Mhz IIRC, while you require 74.25MHz DCLK, so this will not work
> correctly.
> 
> Even if this somehow works by fractional clock being bypassed, I did not design
> the panel mode to be used with CPLL's 800 MHz, but with GPLL frequecy of 594 MHz.
> 
> GPLL 594/74.25 = 8  (integral divider without the need for fractional clock)
> CPLL 800/74.25 = ~10.77441077441077441077
> 
> If you really want to use fractional clock, you'd need to parent it to VPLL
> and set VPLL really high, like close to 2GHz.
>

Thanks for the explanation. Then I just need to squash on top of this, the
following patch. Is that correct?

https://github.com/megous/linux/commit/f19ce7bb7d72

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat