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

[Manivannan Sadhasivam]

On Mon, Sep 21, 2026 at 04:40:43PM +0530, Krishna Chaitanya Chundru wrote:
> 
> 
> On 9/21/2026 2:09 PM, Konrad Dybcio wrote:
> > 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?
> we haven't seen direct problem till now, but we might seen some issue due to
> incorrect LTR_L1.2_THRESHOLD value.

Can you specify what issue can be seen without this series? I'd assume the
link will fail to enter L1.2 and will result in slightly more power drain as
the link can only enter L1.1.

- Mani

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