linux-kernel - Re: [PATCH v7 0/5] PCI/ASPM: Save/restore L1 PM Substates for suspend/resume

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Message-ID: <20240305214656.GA550701@bhelgaas>
Date: Tue, 5 Mar 2024 15:46:56 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: linux-pci@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	"David E . Box" <david.e.box@...ux.intel.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Tasev Nikola <tasev.stefanoska@...net.be>,
	Mark Enriquez <enriquezmark36@...il.com>,
	Thomas Witt <kernel@...t.link>,
	Werner Sembach <wse@...edocomputers.com>,
	Vidya Sagar <vidyas@...dia.com>,
	Kai-Heng Feng <kai.heng.feng@...onical.com>,
	Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
	Ricky Wu <ricky_wu@...ltek.com>,
	Mario Limonciello <mario.limonciello@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v7 0/5] PCI/ASPM: Save/restore L1 PM Substates for
 suspend/resume

On Fri, Feb 23, 2024 at 02:58:46PM -0600, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> This is some rework of David's series to preserve ASPM L1 substate
> configuration across suspend/resume.
> 
> We've had several attempts to make this work:
> 
>   (unlabeled): https://lore.kernel.org/r/20240128233212.1139663-1-david.e.box@linux.intel.com
>   v5: https://lore.kernel.org/r/20231221011250.191599-1-david.e.box@linux.intel.com
>   v4: https://lore.kernel.org/all/20231002070044.2299644-1-mika.westerberg@linux.intel.com/
>   v3: https://lore.kernel.org/linux-pci/20230925074636.2893747-1-mika.westerberg@linux.intel.com/
>   v2: https://lore.kernel.org/linux-pci/20230911073352.3472918-1-mika.westerberg@linux.intel.com/
>   v1: https://lore.kernel.org/linux-pci/20230627062442.54008-1-mika.westerberg@linux.intel.com/
> 
> The most recent posting is the unlabeled one mentioned above, and I'm
> calling it v6 and this rework v7.
> 
> Changes since the unlabeled v6:
> 
>   - Rename pci_save_aspm_state() to pci_save_aspm_l1ss_state() (this
>     is the reason for opening this again, because Vidya's patch [1]
>     had to do some incidental renaming).
> 
>   - Rename pcie_restore_aspm_l1ss() to pci_restore_aspm_l1ss_state()
>     to match.
> 
>   - Move the PCI_EXP_LNKCTL_ASPMC from pci_restore_aspm_state() to
>     pci_restore_pcie_state() so both writes are in the same place.
> 
>   - Rename pci_aspm_get_l1ss() to pci_configure_aspm_l1ss() and add
>     the save_buffer there as well.
> 
>   - Split [1/5] into two patches: move pci_configure_ltr() and
>     pci_bridge_reconfigure_ltr() to aspm.c, and build aspm.c
>     unconditionally.
> 
>   - Squash [2/5] and [3/5] since [2/5] didn't add any functionality
>     itself so they seem like a single logical change.
> 
> [1] https://lore.kernel.org/r/20230125133830.20620-1-vidyas@nvidia.com
> 
> David E. Box (5):
>   PCI/ASPM: Move pci_configure_ltr() to aspm.c
>   PCI/ASPM: Always build aspm.c
>   PCI/ASPM: Move pci_save_ltr_state() to aspm.c
>   PCI/ASPM: Save L1 PM Substates Capability for suspend/resume
>   PCI/ASPM: Call pci_save_ltr_state() from pci_save_pcie_state()
> 
>  drivers/pci/pci.c         |  89 ++++------------
>  drivers/pci/pci.h         |  13 ++-
>  drivers/pci/pcie/Makefile |   2 +-
>  drivers/pci/pcie/aspm.c   | 215 ++++++++++++++++++++++++++++++++++++++
>  drivers/pci/probe.c       |  62 +----------
>  include/linux/pci.h       |   2 +-
>  6 files changed, 252 insertions(+), 131 deletions(-)

I applied these as pci/aspm for v6.9, replacing the original unlabeled
v6 that has been in -next.

I also added the patch I suggested at
https://lore.kernel.org/r/20240223213733.GA115410@bhelgaas to disable
L1 inside pci_restore_aspm_l1ss_state() where we actually depend on it
being disabled.

Bjorn