[PATCH V3 0/2] schemas: pci: bridge: Document PCI L0s & L1 entry delay and N_FTS

Krishna Chaitanya Chundru posted 2 patches 10 months ago
dtschema/schemas/pci/pci-bus-common.yaml | 12 ++++++++++++
1 file changed, 12 insertions(+)
[PATCH V3 0/2] schemas: pci: bridge: Document PCI L0s & L1 entry delay and N_FTS
Posted by Krishna Chaitanya Chundru 10 months ago
Some controllers and endpoints provide provision to program the entry
delays of L0s & L1 which will allow the link to enter L0s & L1 more
aggressively to save power.

Per PCIe r6.0, sec 4.2.5.1, during Link training, a PCIe component
captures the N_FTS value it receives.  Per 4.2.5.6, when
transitioning the Link from L0s to L0, it must transmit N_FTS Fast
Training Sequences to enable the receiver to obtain bit and Symbol
lock.

Components may have device-specific ways to configure N_FTS values
to advertise during Link training.  Define an n-fts array with an
entry for each supported data rate.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
changes in v3:-
- Update the description to specfify about entries of the array (rob)
changes in v2:-
- Split N_FTS & L1 and L0s entry delay in two patches (bjorn)
- Update the commit text, description (bjorn)

Krishna Chaitanya Chundru (2):
  schemas: pci: bridge: Document PCI L0s & L1 entry delay
  schemas: pci: bridge: Document PCIe N_FTS

 dtschema/schemas/pci/pci-bus-common.yaml | 12 ++++++++++++
 1 file changed, 12 insertions(+)

-- 
2.34.1
Re: [PATCH V3 0/2] schemas: pci: bridge: Document PCI L0s & L1 entry delay and N_FTS
Posted by Rob Herring 10 months ago
On Sun, Feb 16, 2025 at 07:15:08AM +0530, Krishna Chaitanya Chundru wrote:
> Some controllers and endpoints provide provision to program the entry
> delays of L0s & L1 which will allow the link to enter L0s & L1 more
> aggressively to save power.
> 
> Per PCIe r6.0, sec 4.2.5.1, during Link training, a PCIe component
> captures the N_FTS value it receives.  Per 4.2.5.6, when
> transitioning the Link from L0s to L0, it must transmit N_FTS Fast
> Training Sequences to enable the receiver to obtain bit and Symbol
> lock.
> 
> Components may have device-specific ways to configure N_FTS values
> to advertise during Link training.  Define an n-fts array with an
> entry for each supported data rate.
> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
> ---
> changes in v3:-
> - Update the description to specfify about entries of the array (rob)
> changes in v2:-
> - Split N_FTS & L1 and L0s entry delay in two patches (bjorn)
> - Update the commit text, description (bjorn)
> 
> Krishna Chaitanya Chundru (2):
>   schemas: pci: bridge: Document PCI L0s & L1 entry delay
>   schemas: pci: bridge: Document PCIe N_FTS
> 
>  dtschema/schemas/pci/pci-bus-common.yaml | 12 ++++++++++++
>  1 file changed, 12 insertions(+)

Applied, thanks.

Rob