Re: [PATCH 3/3] arm64: dts: rockchip: drop max-link-speed = <2> in helios64 PCIe

From: Geraldo Nascimento <geraldogabriel@gmail.com>
To: Dragan Simic <dsimic@manjaro.org>
Cc: linux-rockchip@lists.infradead.org,
	"Shawn Lin" <shawn.lin@rock-chips.com>,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
	"Manivannan Sadhasivam" <mani@kernel.org>,
	"Rob Herring" <robh@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Heiko Stuebner" <heiko@sntech.de>,
	linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Johan Jonker" <jbx6244@gmail.com>
Subject: Re: [PATCH 3/3] arm64: dts: rockchip: drop max-link-speed = <2> in helios64 PCIe
Date: Sat, 15 Nov 2025 06:55:55 -0300	[thread overview]
Message-ID: <aRhOK_aDoJYfgbRJ@geday> (raw)
In-Reply-To: <7d300769-9803-9c0c-60bb-4a724619d8e0@manjaro.org>

On Sat, Nov 15, 2025 at 10:42:40AM +0100, Dragan Simic wrote:
> On Saturday, November 15, 2025 10:36 CET, "Dragan Simic" <dsimic@manjaro.org> wrote:
> > On Saturday, November 15, 2025 10:10 CET, Geraldo Nascimento <geraldogabriel@gmail.com> wrote:
> > > Shawn Lin from Rockchip strongly discourages attempts to use their
> > > RK3399 PCIe core at 5.0 GT/s speed, citing concerns about catastrophic
> > > failures that may happen. Even if the odds are low, drop from last user
> > > of this property for the RK3399 platform, helios64.
> > > 
> > > Fixes: 755fff528b1b ("arm64: dts: rockchip: add variables for pcie completion to helios64")
> > > Link: https://lore.kernel.org/all/ffd05070-9879-4468-94e3-b88968b4c21b@rock-chips.com/
> > > Reported-by: Shawn Lin <shawn.lin@rock-chips.com>
> > > Signed-off-by: Geraldo Nascimento <geraldogabriel@gmail.com>
> > > ---
> > >  arch/arm64/boot/dts/rockchip/rk3399-kobol-helios64.dts | 1 -
> > >  1 file changed, 1 deletion(-)
> > > 
> > > diff --git a/arch/arm64/boot/dts/rockchip/rk3399-kobol-helios64.dts b/arch/arm64/boot/dts/rockchip/rk3399-kobol-helios64.dts
> > > index e7d4a2f9a95e..78a7775c3b22 100644
> > > --- a/arch/arm64/boot/dts/rockchip/rk3399-kobol-helios64.dts
> > > +++ b/arch/arm64/boot/dts/rockchip/rk3399-kobol-helios64.dts
> > > @@ -424,7 +424,6 @@ &pcie_phy {
> > >  
> > >  &pcie0 {
> > >  	ep-gpios = <&gpio2 RK_PD4 GPIO_ACTIVE_HIGH>;
> > > -	max-link-speed = <2>;
> > >  	num-lanes = <2>;
> > >  	pinctrl-names = "default";
> > >  	status = "okay";
> > 
> > Looking good to me, this rounds up the prevention of issues
> > coming from buggy PCIe Gen2 on RK3399.
> > 
> > Please feel free to include
> > 
> > Reviewed-by: Dragan Simic <dsimic@manjaro.org>
> > 
> > Though, could you, please, add patch 4/3 to this series, which
> > would remove the redundant parameter "max-link-speed = <1>" from
> > rk3399-nanopi-r4s.dtsi?
> 
> Sorry, I forgot to note that the patch summary would read a bit
> better if it were reworded like this:
> 
>   arm64: dts: rockchip: Remove redundant max-link-speed from helios64 board dts
>

No, I think:

arm64: dts: rockchip: Remove dangerous max-link-speed from helios64 board dts

Is more accurately described. With focus on the dangerous, we're not
liable.

Redudant max-link-speed only for nanopi-r4s include definitions I think!

Thanks,
Geraldo Nascimento