linux-kernel - [PATCH v2 0/2] PCI: Add missing link delays

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Date:   Fri,  4 Oct 2019 15:39:45 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Len Brown <lenb@...nel.org>, Lukas Wunner <lukas@...ner.de>,
        Keith Busch <keith.busch@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Alexandru Gagniuc <mr.nuke.me@...il.com>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Matthias Andree <matthias.andree@....de>,
        Paul Menzel <pmenzel@...gen.mpg.de>,
        Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/2] PCI: Add missing link delays

Hi,

This is second version of the reworked PCIe link delay patch posted earlier
here:

  https://patchwork.kernel.org/patch/11106611/

Changes from v1:

  * Introduce pcie_wait_for_link_delay() in a separate patch
  * Tidy up changelog, remove some debug output
  * Rename pcie_wait_downstream_accessible() to
    pci_bridge_wait_for_secondary_bus() and make it generic to all PCI
    bridges.
  * Handle Tpvrh + Trhfa for conventional PCI even though we don't do PM
    for them right now.
  * Use pci_dbg() instead of dev_dbg().
  * Dropped check for pm_suspend_no_platform() and only check for D3cold.
  * Drop pcie_get_downstream_delay(), same delay applies equally to all
    devices (it is not entirely clear from the spec).

I'm still checking for downstream device because I think we can skip the
delays if there is nothing connected. The reason is that if device is added
when the downstream/root port is in D3 the delay is handled by pciehp in
its board_added(). In case of ACPI hotplug the firmware is supposed to
configure the device (and handle the delay).

I also checked we do resume sibling devices in paraller (I think due to
async_suspend).

@Matthias, @Paul and @Nicholas, I appreciate if you could check that this
does not cause any issues for your systems.

Mika Westerberg (2):
  PCI: Introduce pcie_wait_for_link_delay()
  PCI: Add missing link delays required by the PCIe spec

 drivers/pci/pci-driver.c |  18 +++++++
 drivers/pci/pci.c        | 113 +++++++++++++++++++++++++++++++++++----
 drivers/pci/pci.h        |   1 +
 3 files changed, 122 insertions(+), 10 deletions(-)

-- 
2.23.0