Re: [PATCH 0/8] arm64: dts: qcom: Add t-power-on-us property for PCIe root ports

[Konrad Dybcio]

On 9/11/26 8:50 AM, Krishna Chaitanya Chundru wrote:
> The Qualcomm PCIe host controller driver added support for parsing the
> -power-on-us property[1] from each Root Port node and programming it as
> art of host initialization (PCI: qcom: Program T_POWER_ON) [2]. Prior to
> this, T_POWER_ON was expected to be programmed correctly in hardware or
> by the bootloader, but not all targets support this, which can lead to an
> incorrectly calculated LTR_L1.2_THRESHOLD in aspm.c and improper L1.2 exit
> behavior.

This is a good problem description. Does it have observable effects
that could also be mentioned here, beyond perhaps lspci reporting
an odd value?


> This series adds the t-power-on-us = <80>; property to the PCIe root
> port node(s) on the following targets, so the controller programs the
> correct T_POWER_ON value instead of relying on the (currently incorrect)
> hardware default:
> 
> - kodiak
> - lemans
> - monaco
> - hamoa
> - glymur
> - talos
> - sm8750
> - kaanapali

Because you said "currently incorrect", it clearly applies to all of
these platforms. Are other ones that we support in the tree also
affected?

Konrad