linux-kernel - Re: [PATCH 2/2] clk: mvebu: cp110 add CLK_IGNORE_UNUSED to pcie_x10, pcie_x11 & pcie

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Message-ID: <481bf79f-0cec-498f-9827-f4c6dfd6c14e@solid-run.com>
Date: Thu, 30 Oct 2025 15:51:35 +0000
From: Josua Mayer <josua@...id-run.com>
To: Andrew Lunn <andrew@...n.ch>
CC: Gregory Clement <gregory.clement@...tlin.com>, Sebastian Hesselbarth
	<sebastian.hesselbarth@...il.com>, Rob Herring <robh@...nel.org>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Michael
 Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Rabeeh
 Khoury <rabeeh@...id-run.com>, Yazan Shhady <yazan.shhady@...id-run.com>,
	Mikhail Anikin <mikhail.anikin@...id-run.com>, Jon Nettleton
	<jon@...id-run.com>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-clk@...r.kernel.org"
	<linux-clk@...r.kernel.org>
Subject: Re: [PATCH 2/2] clk: mvebu: cp110 add CLK_IGNORE_UNUSED to pcie_x10,
 pcie_x11 & pcie_x4

I missed a colon in the subject line "cp110:",
should I roll v2 for this?

Am 30.10.25 um 16:33 schrieb Andrew Lunn:
> On Thu, Oct 30, 2025 at 04:16:26PM +0100, Josua Mayer wrote:
>> CP110 based platforms rely on the bootloader for pci port
>> initialization.
>> TF-A actively prevents non-uboot re-configuration of pci lanes, and many
>> boards do not have software control over the pci card reset.
>>
>> If a pci port had link at boot-time and the clock is stopped at a later
>> point, the link fails and can not be recovered.
>>
>> PCI controller driver probe - and by extension ownership of a driver for
>> the pci clocks - may be delayed especially on large modular kernels,
>> causing the clock core to start disabling unused clocks.
>>
>> Add the CLK_IGNORE_UNUSED flag to the three pci port's clocks to ensure
>> they are not stopped before the pci controller driver has taken
>> ownership and tested for an existing link.
>>
>> This fixes failed pci link detection when controller driver probes late,
>> e.g. with arm64 defconfig and CONFIG_PHY_MVEBU_CP110_COMPHY=m.
> Seems like a reasonable compromise, given that TF-A could be classed
> as broken. This must also prevent suspend/resume powering off PCI
> devices, and then reconnecting them on resume.
Currently pcie-armada8k (unlike e.g. pci-imx6) does not currently define
any dev_pm_ops - so we should be safe from any power-management.
>
> Reviewed-by: Andrew Lunn <andrew@...n.ch>
>
>     Andrew