Re: [PATCH v5 1/2] PCI: dwc: Implement general suspend/resume functionality for L2/L3 transitions

On Fri, Jul 28, 2023 at 11:05:56AM +0200, Lorenzo Pieralisi wrote:

On Mon, Jul 24, 2023 at 05:58:29PM -0400, Frank Li wrote:

quoted

Introduced helper function dw_pcie_get_ltssm to retrieve SMLH_LTSS_STATE.
Added API pme_turn_off and exit_from_l2 for managing L2/L3 state transitions.

Commit logs should not use the past tense but the present tense.

eg s/Introduced/Introduce

Furthermore, read this post from Bjorn and follow it to the letter
please:

https://lore.kernel.org/linux-pci/20171026223701.GA25649@bhelgaas-glaptop.roam.corp.google.com (local)

quoted

Typical L2 entry workflow:

1. Transmit PME turn off signal to PCI devices and wait for PME_To_Ack.
2. Await link entering L2_IDLE state.
3. Transition Root complex to D3 state.

Typical L2 exit workflow:

1. Transition Root complex to D0 state.
2. Issue exit from L2 command.
3. Reinitialize PCI host.
4. Wait for link to become active.

This does not explain what the patch does and why it does it.

Are you describing the L2 entry/exit as implemented in the code ?

Yes.

How about below commit message:

Introduce helper function dw_pcie_get_ltssm to retrieve SMLH_LTSS_STATE.

Add callback .pme_turn_off and .exit_from_l2 for platform specific PME
handle.

Add common dw_pcie_suspend(resume)_noirq() API to avoid duplicated code
in dwc pci host controller platform driver.

Typical L2 entry workflow/dw_pcie_suspend_noirq()

1. Transmit PME turn off signal to PCI devices and wait for PME_To_Ack.
2. Await link entering L2_IDLE state.
3. Transition Root complex to D3 state.

Typical L2 exit workflow/dw_pcie_resume_noirq()

1. Transition Root complex to D0 state.
2. Issue exit from L2 command.
3. Reinitialize PCI host.
4. Wait for link to become active.

Frank

quoted

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Change from v4 to v5: