Re: [PATCH v2] PCI: dw-rockchip: Disable L1 substates

[Niklas Cassel <cassel@kernel.org>]

On Thu, Oct 16, 2025 at 12:25:04PM -0500, Bjorn Helgaas wrote:
> On Thu, Oct 16, 2025 at 11:04:22AM +0200, Niklas Cassel wrote:
> > The L1 substates support requires additional steps to work, see e.g.
> > section '11.6.6.4 L1 Substate' in the RK3588 TRM V1.0.
> > 
> > These steps are currently missing from the driver.
> 
> Can we outline here specifically what is missing?

Sure.

> 
> > While this has always been a problem when using e.g.
> > CONFIG_PCIEASPM_POWER_SUPERSAVE=y, the problem became more apparent after
> > commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for
> > devicetree platforms"), which enabled ASPM also for
> > CONFIG_PCIEASPM_DEFAULT=y.
> 
> Should also be able to trigger this problem regardless of
> CONFIG_PCIEASPM_* by using /sys/bus/pci/devices/.../link/l1_2_aspm.
> 
> > Disable L1 substates until proper support is added.
> 
> I would word this more like "prevent advertising L1 Substates support"
> since we're not actually *disabling* anything here.

Sure.

> 
> If the RK3588 TRM is publicly available, a URL here would be helpful.

I couldn't find it on any official rockchip or radxa URL.


Will submit a v3 that fixes your comments.


Kind regards,
Niklas