linux-kernel - Re: [PATCH v2 4/4] arm64: dts: rockchip: Make Jaguar PCIe-refclk pin use pull-up config

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Message-ID: <ef0569ca-bf27-4e64-bee1-4eba551b91c1@cherry.de>
Date: Tue, 10 Feb 2026 10:50:37 +0100
From: Quentin Schulz <quentin.schulz@...rry.de>
To: Heiko Stuebner <heiko@...ech.de>
Cc: linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org, Heiko Stuebner <heiko.stuebner@...rry.de>
Subject: Re: [PATCH v2 4/4] arm64: dts: rockchip: Make Jaguar PCIe-refclk pin
 use pull-up config

Hi Heiko,

On 2/10/26 9:03 AM, Heiko Stuebner wrote:
> From: Heiko Stuebner <heiko.stuebner@...rry.de>
> 
> Different to RK3588-Tiger, on RK3588-Jaguar the signal enabling the
> PCIe-refclk generator controls a transistor which in turn controls the
> output-enable input of the PI6C557 and there's no external Pull-Up or
> Pull-Down between the SoC and the transistor gate.
> 
> On Tiger the pin is directly connected to the PDn input which has an
> internal pull up.
> 
> So match that behaviour on Jaguar by changing the pin config to enable
> the SoC's pull-up config.
> 

I think we've a different behavior on Jaguar and Tiger (see polarity of 
enable-gpios), so this is a bit misleading. I would simply say this 
matches the default PU/PD pinconf of the SoC after reset according to 
the TRM. It also means we keep the clock generator in reset until the 
device driver drives the enable pin. On Tiger, since we would need a 
pull-down to have it disabled by default, but that it's only an internal 
pull-down on RK3588-side and a pull-up on the clock generator IC-side, I 
don't know if that would work and reliably at that if we were to have 
opposite internal pull-up/down resistors on each side of the line, hence 
the no PU/PD on RK3588 side.

With the commit log reworked:

Reviewed-by: Quentin Schulz <quentin.schulz@...rry.de>

Thanks!
Quentin