linux-kernel - Re: [PATCH] PCI: dw-rockchip: Skip waiting for link up

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Message-ID: <E739D84F1F86AA6E+92a19e8b-ce67-4fb2-aa74-f5e5b0a075d3@radxa.com>
Date: Mon, 10 Nov 2025 08:16:40 +0900
From: FUKAUMI Naoki <naoki@...xa.com>
To: Niklas Cassel <cassel@...nel.org>
Cc: Shawn Lin <shawn.lin@...k-chips.com>, Damien Le Moal
 <dlemoal@...nel.org>, Anand Moon <linux.amoon@...il.com>,
 linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Dragan Simic <dsimic@...jaro.org>, Lorenzo Pieralisi
 <lpieralisi@...nel.org>, Krzysztof Wilczyński
 <kw@...ux.com>, Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Heiko Stuebner <heiko@...ech.de>
Subject: Re: [PATCH] PCI: dw-rockchip: Skip waiting for link up

Hi Niklas,

On 11/9/25 21:28, Niklas Cassel wrote:
> On Sun, Nov 09, 2025 at 01:42:23PM +0900, FUKAUMI Naoki wrote:
>> Hi Niklas,
>>
>> On 11/8/25 22:27, Niklas Cassel wrote:
>> (snip)> (And btw. please test with the latest 6.18-rc, as, from experience,
>> the
>>> ASPM problems in earlier RCs can result in some weird problems that are
>>> not immediately deduced to be caused by the ASPM enablement.)
>>
>> Here is dmesg from v6.18-rc4:
>>   https://gist.github.com/RadxaNaoki/40e1d049bff4f1d2d4773a5ba0ed9dff
> 
> Same problem as before:
> [    1.732538] pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> [    1.732645] pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
> [    1.732651] pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
> [    1.732661] pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
> [    1.732840] pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> [    1.732947] pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
> [    1.732952] pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
> [    1.732962] pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
> [    1.733134] pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> [    1.733246] pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
> [    1.733255] pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
> [    1.733266] pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
> [    1.733438] pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> [    1.733544] pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
> [    1.733550] pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
> [    1.733560] pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
> [    1.733571] pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
> [    1.733575] pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
> [    1.733585] pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
> [    1.733596] pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46
> 
> 
> Seems like the ASM2806 switch, for some reason, is not ready.
> 
> One change that Diederik pointed out is that in the "good" case,
> the link is always in Gen1 speed.
> 
> Perhaps you could build with CONFIG_PCI_QUIRKS=y and try this patch:
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 214ed060ca1b..ac134d95a97f 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -96,6 +96,7 @@ int pcie_failed_link_retrain(struct pci_dev *dev)
>   {
>   	static const struct pci_device_id ids[] = {
>   		{ PCI_VDEVICE(ASMEDIA, 0x2824) }, /* ASMedia ASM2824 */
> +		{ PCI_VDEVICE(ASMEDIA, 0x2806) }, /* ASMedia ASM2806 */
>   		{}
>   	};
>   	u16 lnksta, lnkctl2;

It doesn't help with either probing behind the bridge or the link speed.

> If that does not work, perhaps you could try this patch
> (assuming that all Rock 5C:s have a ASM2806 on pcie2x1l2):

ROCK 5C has a PCIe FPC connector and I'm using Dual 2.5G Router HAT.
  https://radxa.com/products/rock5/5c#techspec
  https://radxa.com/products/accessories/dual-2-5g-router-hat

Regarding the link speed, I initially suspected the FPC connector and/or 
cable might be the issue. However, I tried the Dual 2.5G Router HAT with 
the ROCK 5A (which uses a different cable), and I got the same result.

BTW, the link speed varies between 2Gb/s and 4Gb/s depending on the 
reboot. (with or without quirk)

Best regards,

--
FUKAUMI Naoki
Radxa Computer (Shenzhen) Co., Ltd.

> diff --git a/arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts b/arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts
> index dd7317bab613..26f8539d934a 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3588s-rock-5c.dts
> @@ -452,6 +452,7 @@ &pcie2x1l2 {
>   	pinctrl-0 = <&pcie20x1_2_perstn_m0>;
>   	reset-gpios = <&gpio3 RK_PD1 GPIO_ACTIVE_HIGH>;
>   	vpcie3v3-supply = <&pcie2x1l2_3v3>;
> +	max-link-speed = <1>;
>   	status = "okay";
>   };
> 
> 
> 
> Kind regards,
> Niklas
>