- Fix s390 build error (Pali Rohár)

- Check for errors from pci_bridge_emul_init() (Pali Rohár)

- Export pci-bridge-emul functions for use by modules (Pali Rohár)

- Make aardvark driver modular (Pali Rohár)

- Move PCIe reset code to advk_pcie_train_link() (Pali Rohár)

- Convert internal SMCC firmware return codes to errno (Pali Rohár)

- Fix initialization with old Marvell's Arm Trusted Firmware (Pali Rohár)

* remotes/lorenzo/pci/aardvark:
  PCI: aardvark: Fix initialization with old Marvell's Arm Trusted Firmware
  phy: marvell: comphy: Convert internal SMCC firmware return codes to errno
  PCI: aardvark: Move PCIe reset card code to advk_pcie_train_link()
  PCI: aardvark: Implement driver 'remove' function and allow to build it as module
  PCI: pci-bridge-emul: Export API functions
  PCI: aardvark: Check for errors from pci_bridge_emul_init() call
  PCI: aardvark: Fix compilation on s390

- Remove unused msi_ctrl, io_optional and align_resource fields from ARM
  struct hw_pci (Lorenzo Pieralisi)

* remotes/lorenzo/pci/arm:
  ARM/PCI: Remove unused fields from struct hw_pci

- Remove useless __KERNEL__ preprocessor guard in sparc io_32.h (Lorenzo
  Pieralisi)

- Move ioremap/iounmap declaration so it's visible in asm-generic/io.h
  (Lorenzo Pieralisi)

- Fix memory leak in generic !CONFIG_GENERIC_IOMAP pci_iounmap()
  implementation (Lorenzo Pieralisi)

* remotes/lorenzo/pci/pci-iomap:
  asm-generic/io.h: Fix !CONFIG_GENERIC_IOMAP pci_iounmap() implementation
  sparc32: Move ioremap/iounmap declaration before asm-generic/io.h include
  sparc32: Remove useless io_32.h __KERNEL__ preprocessor guard

- Add ACPI APEI notifier chain for unknown (vendor) CPER records (Shiju
  Jose)

- Add handling of HiSilicon HIP PCIe controller errors (Yicong Yang)

* remotes/lorenzo/pci/apei:
  PCI: hip: Add handling of HiSilicon HIP PCIe controller errors
  ACPI / APEI: Add a notifier chain for unknown (vendor) CPER records

- Remove unnecessary #includes (Gustavo Pimentel)

- Fix intel_mid_pci.c build error when !CONFIG_ACPI (Randy Dunlap)

- Use scnprintf(), not snprintf(), in sysfs "show" functions (Krzysztof
  Wilczyński)

- Simplify pci-pf-stub by using module_pci_driver() (Liu Shixin)

- Print IRQ used by Link Bandwidth Notification (Dongdong Liu)

- Update sysfs mmap-related #ifdef comments (Clint Sbisa)

- Simplify pci_dev_reset_slot_function() (Lukas Wunner)

- Use "NULL" instead of "0" to fix sparse warnings (Gustavo Pimentel)

- Simplify bool comparisons (Krzysztof Wilczyński)

- Drop double zeroing for P2PDMA sg_init_table() (Julia Lawall)

* pci/misc:
  PCI: v3-semi: Remove unneeded break
  PCI/P2PDMA: Drop double zeroing for sg_init_table()
  PCI: Simplify bool comparisons
  PCI: endpoint: Use "NULL" instead of "0" as a NULL pointer
  PCI: Simplify pci_dev_reset_slot_function()
  PCI: Update mmap-related #ifdef comments
  PCI/LINK: Print IRQ number used by port
  PCI/IOV: Simplify pci-pf-stub with module_pci_driver()
  PCI: Use scnprintf(), not snprintf(), in sysfs "show" functions
  x86/PCI: Fix intel_mid_pci.c build error when ACPI is not enabled
  PCI: Remove unnecessary header includes

- Remove unused pcibios_pm_ops (Vaibhav Gupta)

- Rename pci_dev.d3_delay to d3hot_delay (Krzysztof Wilczyński)

- Apply D2 transition delay as microseconds, not milliseconds (Bjorn
  Helgaas)

* pci/pm:
  PCI/PM: Revert "PCI/PM: Apply D2 delay as milliseconds, not microseconds"
  PCI/PM: Remove unused PCI_PM_BUS_WAIT
  PCI/PM: Rename pci_dev.d3_delay to d3hot_delay
  PCI/PM: Remove unused pcibios_pm_ops

- Use for_each_child_of_node() and for_each_node_by_name() instead of
  open-coding them (Qinglang Miao)

- Reduce pciehp noisiness on hot removal (Lukas Wunner)

- Remove unused assignment in shpchp (Krzysztof Wilczyński)

* pci/hotplug:
  PCI: shpchp: Remove unused 'rc' assignment
  PCI: pciehp: Reduce noisiness on hot removal
  PCI: rpadlpar: Use for_each_child_of_node() and for_each_node_by_name()

- Tone down message about missing optional MCFG (Jeremy Linton)

- Add schedule point in pci_read_config() (Jiang Biao)

- Add Ampere Altra SOC MCFG quirk (Tuan Phan)

- Add Kconfig options for MPS/MRRS strategy (Jim Quinlan)

* pci/enumeration:
  PCI: Add Kconfig options for MPS/MRRS strategy
  PCI/ACPI: Add Ampere Altra SOC MCFG quirk
  PCI: Add schedule point in pci_read_config()
  PCI/ACPI: Tone down missing MCFG message

- Remove struct aspm_register_info (Saheed O. Bolarinwa)

- Remove struct pcie_link_state.l1ss (Saheed O. Bolarinwa)

* pci/aspm:
  PCI/ASPM: Remove struct pcie_link_state.l1ss
  PCI/ASPM: Remove struct aspm_register_info.l1ss_cap
  PCI/ASPM: Pass L1SS Capabilities value, not struct aspm_register_info
  PCI/ASPM: Remove struct aspm_register_info.l1ss_ctl1
  PCI/ASPM: Remove struct aspm_register_info.l1ss_ctl2 (unused)
  PCI/ASPM: Remove struct aspm_register_info.l1ss_cap_ptr
  PCI/ASPM: Remove struct aspm_register_info.latency_encoding
  PCI/ASPM: Remove struct aspm_register_info.enabled
  PCI/ASPM: Remove struct aspm_register_info.support
  PCI/ASPM: Use 'parent' and 'child' for readability
  PCI/ASPM: Move LTR path check to where it's used
  PCI/ASPM: Move pci_clear_and_set_dword() earlier

- Enable Translation Blocking for external devices (Rajat Jain)

* pci/acs:
  PCI/ACS: Enable Translation Blocking for external devices

A break is not needed if it is preceded by a return

Link: https://lore.kernel.org/r/20201019190249.7825-1-trix@redhat.comSigned-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Previously we computed L1.2 parameters in the enumeration path, saved them
in struct pcie_link_state.l1ss, and programmed them into the devices
whenever we enabled or disabled L1.2 on the link.  But these parameters are
constant and don't need to be updated when enabling/disabling L1.2.

Compute and program the L1.2 parameters once during enumeration and remove
the struct pcie_link_state.l1ss member.  No functional change intended.

[bhelgaas: rework to program L1.2 parameters during enumeration]
Link: https://lore.kernel.org/r/20201015193039.12585-13-helgaas@kernel.orgSigned-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Previously we stored the L1SS Capabilities value in the struct
aspm_register_info.

We only need this information in one place, so read it there and remove
struct aspm_register_info completely, since it's now empty.  No functional
change intended.

[bhelgaas: split up, don't cache l1ss_cap in pci_dev]
Link: https://lore.kernel.org/r/20201015193039.12585-12-helgaas@kernel.orgSigned-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

aspm_calc_l1ss_info() needs only the L1SS Capabilities.  It doesn't need
anything else from struct aspm_register_info, so pass only the Capabilities
value.  No functional change intended.

Link: https://lore.kernel.org/r/20201015193039.12585-11-helgaas@kernel.orgSigned-off-by: Bjorn Helgaas <bhelgaas@google.com>

Previously we stored the L1SS Control 1 register in the struct
aspm_register_info.

We only need this information in one place, so read it there and remove it
from struct aspm_register_info.  No functional change intended.

[bhelgaas: split ctl1/ctl2]
Link: https://lore.kernel.org/r/20201015193039.12585-10-helgaas@kernel.orgSigned-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

We never use the aspm_register_info.l1ss_ctl2 value, so remove it.  No
functional change intended.

Link: https://lore.kernel.org/r/20201015193039.12585-9-helgaas@kernel.orgSigned-off-by: Bjorn Helgaas <bhelgaas@google.com>

Save the L1 Substates Capability pointer in struct pci_dev.  Then we don't
have to keep track of it in the struct aspm_register_info and struct
pcie_link_state, which makes the code easier to read.  No functional change
intended.

[bhelgaas: split to a separate patch]
Link: https://lore.kernel.org/r/20201015193039.12585-8-helgaas@kernel.orgSigned-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Previously we stored L0s and L1 Exit Latency information from the Link
Capabilities register in the struct aspm_register_info.

We only need these latencies when we already have the Link Capabilities
values, so use those directly and remove the latencies from struct
aspm_register_info.  No functional change intended.

Link: https://lore.kernel.org/r/20201015193039.12585-7-helgaas@kernel.orgSigned-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Previously we stored the "ASPM Control" bits from the Link Control register
in the struct aspm_register_info.

Read PCI_EXP_LNKCTL directly when needed.  This means we can use the
PCI_EXP_LNKCTL_ASPM_* bits directly instead of the similar but different
PCIE_LINK_STATE_* bits.  No functional change intended.

[bhelgaas: drop get_aspm_enable() and read LNKCTL once directly]
Link: https://lore.kernel.org/r/20201015193039.12585-6-helgaas@kernel.orgSigned-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Previously we stored the "ASPM Support" field from the Link Capabilities
register in the struct aspm_register_info.

Read the Link Capabilities directly when needed and remove it from the
struct aspm_register_info.  No functional change intended.

[bhelgaas: remove pci_dev cached copy since LNKCAP isn't truly read-only,
add PCI_EXP_LNKCAP_ASPM_L0S & PCI_EXP_LNKCAP_ASPM_L1, check them directly
instead of adding aspm_support()]
Link: https://lore.kernel.org/r/20201015193039.12585-5-helgaas@kernel.orgSigned-off-by: Saheed O. Bolarinwa <refactormyself@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Other users of link->pdev and link->downstream, e.g., pcie_aspm_cap_init(),
pcie_config_aspm_l1ss(), and pcie_config_aspm_link(), use "parent" and
"child" as local names.

Do the same in aspm_calc_l1ss_info() for readability.  No functional change
intended.

Link: https://lore.kernel.org/r/20201015193039.12585-4-helgaas@kernel.orgSigned-off-by: Bjorn Helgaas <bhelgaas@google.com>

pcie_get_aspm_reg() mostly reads ASPM-related registers, but in some cases
it also updates the value read from PCI_L1SS_CAP based on LTR properties.

Move this update to the point where the value is used to make the code more
readable.

No functional change intended, although previously we could clear
PCI_L1SS_CAP_ASPM_L1_2 for both ends of the link, and now we'll only do it
for the downstream end of a link.  This shouldn't matter because we always
test that bit by ANDing l1ss_cap for the upstream and downstream ends.

Link: https://lore.kernel.org/r/20201015193039.12585-3-helgaas@kernel.orgSigned-off-by: Bjorn Helgaas <bhelgaas@google.com>

Move pci_clear_and_set_dword() earlier in file to prepare for future patch.
No functional change intended.

Link: https://lore.kernel.org/r/20201015193039.12585-2-helgaas@kernel.orgSigned-off-by: Bjorn Helgaas <bhelgaas@google.com>

For arches that do not select CONFIG_GENERIC_IOMAP, the current
pci_iounmap() function does nothing causing obvious memory leaks
for mapped regions that are backed by MMIO physical space.

In order to detect if a mapped pointer is IO vs MMIO, a check must made
available to the pci_iounmap() function so that it can actually detect
whether the pointer has to be unmapped.

In configurations where CONFIG_HAS_IOPORT_MAP && !CONFIG_GENERIC_IOMAP,
a mapped port is detected using an ioport_map() stub defined in
asm-generic/io.h.

Use the same logic to implement a stub (ie __pci_ioport_unmap()) that
detects if the passed in pointer in pci_iounmap() is IO vs MMIO to
iounmap conditionally and call it in pci_iounmap() fixing the issue.

Leave __pci_ioport_unmap() as a NOP for all other config options.
Tested-by: George Cherian <george.cherian@marvell.com>
Link: https://lore.kernel.org/lkml/20200905024811.74701-1-yangyingliang@huawei.com
Link: https://lore.kernel.org/lkml/20200824132046.3114383-1-george.cherian@marvell.com
Link: https://lore.kernel.org/r/a9daf8d8444d0ebd00bc6d64e336ec49dbb50784.1600254147.git.lorenzo.pieralisi@arm.comReported-by: George Cherian <george.cherian@marvell.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: George Cherian <george.cherian@marvell.com>
Cc: Will Deacon <will@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Yang Yingliang <yangyingliang@huawei.com>

Move the ioremap/iounmap declaration before asm-generic/io.h is
included so that it is visible within it.

Link: https://lore.kernel.org/r/93e2f23cda474a92a4708d4c50c9c359426a2162.1600254147.git.lorenzo.pieralisi@arm.comSigned-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: "David S. Miller" <davem@davemloft.net>
Cc: "David S. Miller" <davem@davemloft.net>

The __KERNEL_ preprocessor guard is useless in non-uapi headers.

Remove it.

Link: https://lore.kernel.org/r/084753d3064fe946ff1963eda2eb425cfd7daa7b.1600254147.git.lorenzo.pieralisi@arm.comSigned-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: David S. Miller <davem@davemloft.net>

Old ATF automatically power on pcie phy and does not provide SMC call for
phy power on functionality which leads to aardvark initialization failure:

[    0.330134] mvebu-a3700-comphy d0018300.phy: unsupported SMC call, try updating your firmware
[    0.338846] phy phy-d0018300.phy.1: phy poweron failed --> -95
[    0.344753] advk-pcie d0070000.pcie: Failed to initialize PHY (-95)
[    0.351160] advk-pcie: probe of d0070000.pcie failed with error -95

This patch fixes above failure by ignoring 'not supported' error in
aardvark driver. In this case it is expected that phy is already power on.
Tested-by: Tomasz Maciej Nowak <tmn505@gmail.com>
Link: https://lore.kernel.org/r/20200902144344.16684-3-pali@kernel.org
Fixes: 36669701 ("PCI: aardvark: Add PHY support")
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: <stable@vger.kernel.org> # 5.8+: ea17a0f1: phy: marvell: comphy: Convert internal SMCC firmware return codes to errno

Driver ->power_on and ->power_off callbacks leaks internal SMCC firmware
return codes to phy caller. This patch converts SMCC error codes to
standard linux errno codes. Include file linux/arm-smccc.h already provides
defines for SMCC error codes, so use them instead of custom driver defines.
Note that return value is signed 32bit, but stored in unsigned long type
with zero padding.
Tested-by: Tomasz Maciej Nowak <tmn505@gmail.com>
Link: https://lore.kernel.org/r/20200902144344.16684-2-pali@kernel.orgSigned-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>

Add Kconfig options for changing the default pcie_bus_config, i.e., the
strategy for configuration MPS and MRRS, in the same manner as the
CONFIG_PCIEASPM_XXXX choice.  The pci_bus_config setting may still be
overridden by kernel command-line parameters, e.g.,
"pci=pcie_bus_tune_off".

[bhelgaas: depend on EXPERT, tweak help texts]
Link: https://lore.kernel.org/r/20200928194651.5393-2-james.quinlan@broadcom.comSigned-off-by: Jim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

This reverts commit 7e24bc34.

7e24bc34 was based on PCIe r5.0, sec 5.9, which claims we need a 200 ms
delay when transitioning to or from D2.  However, sec 5.3.1.3 states the
delay as 200 μs (microseconds), as does the table in PCIe r4.0, sec 5.9.1.

This looks like a typo in the r5.0 spec, so revert back to a 200 μs delay
instead of a 200 ms delay.

Fixes: 7e24bc34 ("PCI/PM: Apply D2 delay as milliseconds, not microseconds")
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

476e7fae ("PCI PM: Do not wait for buses in B2 or B3 during resume")
removed the last use of PCI_PM_BUS_WAIT.  Remove the definition as well.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

sg_init_table() zeroes its first argument, so the allocation of that
argument doesn't have to.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

  // <smpl>
  @@
  expression x;
  @@

  x =
  - kzalloc
  + kmalloc
   (...)
  ...
  sg_init_table(x,...)
  // </smpl>

Link: https://lore.kernel.org/r/1600601186-7420-15-git-send-email-Julia.Lawall@inria.frSigned-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Take care about Coccinelle warnings:

  drivers/pci/pci.c:6008:6-12: WARNING: Comparison to bool
  drivers/pci/pci.c:6024:7-13: WARNING: Comparison to bool

No change to functionality intended.

Link: https://lore.kernel.org/r/20200925224555.1752460-1-kw@linux.comSigned-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI devices support two variants of the D3 power state: D3hot (main power
present) D3cold (main power removed).  Previously struct pci_dev contained:

  unsigned int    d3_delay;       /* D3->D0 transition time in ms */
  unsigned int    d3cold_delay;   /* D3cold->D0 transition time in ms */

"d3_delay" refers specifically to the D3hot state.  Rename it to
"d3hot_delay" to avoid ambiguity and align with the ACPI "_DSM for
Specifying Device Readiness Durations" in the PCI Firmware spec r3.2,
sec 4.6.9.

There is no change to the functionality.

Link: https://lore.kernel.org/r/20200730210848.1578826-1-kw@linux.comSigned-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

The "struct dev_pm_ops pcibios_pm_ops", declared in include/linux/pci.h and
defined in drivers/pci/pci-driver.c, provided arch-specific hooks when a
PCI device was doing a hibernate transition.

39421627 ("s390: remove broken hibernate / power management support")
removed the last use of pcibios_pm_ops, so remove it completely.

[bhelgaas: drop unused "error"]
Link: https://lore.kernel.org/r/20200730194416.1029509-1-vaibhavgupta40@gmail.comReported-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

The value of the constant POWER_FAILURE assigned to the variable rc
after the power fault check is never used for anything, so remove it.

Addresses-Coverity-ID: 1226899 ("Unused value")
Link: https://lore.kernel.org/r/20200923025225.471459-1-kw@linux.comSigned-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

The msi_ctrl, io_optional and align_resource fields in struct hw_pci are
currently unused by arm/mach PCI host controller drivers and we won't
be adding any new users.

Remove them and related code.

Link: https://lore.kernel.org/r/20200904141607.4066-1-lorenzo.pieralisi@arm.com
Link: https://lore.kernel.org/r/20200916103045.28651-1-lorenzo.pieralisi@arm.comSigned-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>

When returning a NULL pointer, use "NULL" instead of "0".

Fixes sparse warning given by executing "make C=2 drivers/pci/":

  CHECK   drivers/pci/endpoint/pci-epc-core.c
   drivers/pci/endpoint/pci-epc-core.c: note: in included file:
   ./include/linux/pci-ep-cfs.h:22:16: warning:
   Using plain integer as NULL pointer
  CHECK   drivers/pci/endpoint/pci-epf-core.c
   drivers/pci/endpoint/pci-epf-core.c: note: in included file:
   ./include/linux/pci-ep-cfs.h:31:16: warning:
   Using plain integer as NULL pointer

Link: https://lore.kernel.org/r/80895f7465719edb3aa259e907acc4bc3217945c.1600378209.git.gustavo.pimentel@synopsys.comReported-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Joao Pinto <jpinto@synopsys.com>

pci_dev_reset_slot_function() refuses to reset a hotplug slot if it is
shared by multiple pci_devs.  That's the case if and only if the slot is
occupied by a multifunction device.

Simplify the function to check the device's multifunction flag instead
of iterating over the devices on the bus.  (Iterating over the devices
requires holding pci_bus_sem, which the function erroneously does not
acquire.)

Link: https://lore.kernel.org/r/c6aab5af096f7b1b3db57f6335cebba8f0fcca89.1595330431.git.lukas@wunner.deSigned-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Alex Williamson <alex.williamson@redhat.com>

When a PCIe card is hot-removed, the Presence Detect State and Data Link
Layer Link Active bits often do not clear simultaneously.  I've seen delays
of up to 244 msec between the two events with Thunderbolt.

After pciehp has brought down the slot in response to the first event, the
other bit may still be set.  It's not discernible whether it's set because
a new card is already in the slot or if it will soon clear.  So pciehp
tries to bring up the slot and in the latter case fails with a bunch of
messages, some of them at KERN_ERR severity.  If the slot is no longer
occupied, the messages are false positives and annoy users.

Stuart Hayes reports the following splat on hot removal:

  KERN_INFO pcieport 0000:3c:06.0: pciehp: Slot(180): Link Up
  KERN_INFO pcieport 0000:3c:06.0: pciehp: Timeout waiting for Presence Detect
  KERN_ERR  pcieport 0000:3c:06.0: pciehp: link training error: status 0x0001
  KERN_ERR  pcieport 0000:3c:06.0: pciehp: Failed to check link status

Dongdong Liu complains about a similar splat:

  KERN_INFO pciehp 0000:80:10.0:pcie004: Slot(36): Link Down
  KERN_INFO iommu: Removing device 0000:87:00.0 from group 12
  KERN_INFO pciehp 0000:80:10.0:pcie004: Slot(36): Card present
  KERN_INFO pcieport 0000:80:10.0: Data Link Layer Link Active not set in 1000 msec
  KERN_ERR  pciehp 0000:80:10.0:pcie004: Failed to check link status

Users are particularly irritated to see a bringup attempt even though the
slot was explicitly brought down via sysfs.  In a perfect world, we could
avoid this by setting Link Disable on slot bringdown and re-enabling it
upon a Presence Detect State change.  In reality however, there are broken
hotplug ports which hardwire Presence Detect to zero, see 80696f99
("PCI: pciehp: Tolerate Presence Detect hardwired to zero").  Conversely,
PCIe r1.0 hotplug ports hardwire Link Active to zero because Link Active
Reporting wasn't specified before PCIe r1.1.  On unplug, some ports first
clear Presence then Link (see Stuart Hayes' splat) whereas others use the
inverse order (see Dongdong Liu's splat).  To top it off, there are hotplug
ports which flap the Presence and Link bits on slot bringup, see
6c35a1ac ("PCI: pciehp: Tolerate initially unstable link").

pciehp is designed to work with all of these variants.  Surplus attempts at
slot bringup are a lesser evil than not being able to bring up slots at
all.  Although we could try to perfect the behavior for specific hotplug
controllers, we'd risk breaking others or increasing code complexity.

But we can certainly minimize annoyance by emitting only a single message
with KERN_INFO severity if bringup is unsuccessful:

* Drop the "Timeout waiting for Presence Detect" message in
  pcie_wait_for_presence().  The sole caller of that function,
  pciehp_check_link_status(), ignores the timeout and carries on.  It emits
  error messages of its own and I don't think this particular message adds
  much value.

* There's a single error condition in pciehp_check_link_status() which
  does not emit a message.  Adding one allows dropping the "Failed to check
  link status" message emitted by board_added() if
  pciehp_check_link_status() returns a non-zero integer.

* Tone down all messages in pciehp_check_link_status() to KERN_INFO
  severity and rephrase them to look as innocuous as possible.  To this
  end, move the message emitted by pcie_wait_for_link_delay() to its
  callers.

As a result, Stuart Hayes' splat becomes:

  KERN_INFO pcieport 0000:3c:06.0: pciehp: Slot(180): Link Up
  KERN_INFO pcieport 0000:3c:06.0: pciehp: Slot(180): Cannot train link: status 0x0001

Dongdong Liu's splat becomes:

  KERN_INFO pciehp 0000:80:10.0:pcie004: Slot(36): Card present
  KERN_INFO pciehp 0000:80:10.0:pcie004: Slot(36): No link

The messages now merely serve as information that presence or link bits
were set a little longer than expected.  Bringup failures which are not
false positives are still reported, albeit no longer at KERN_ERR severity.

Link: https://lore.kernel.org/linux-pci/20200310182100.102987-1-stuart.w.hayes@gmail.com/
Link: https://lore.kernel.org/linux-pci/1547649064-19019-1-git-send-email-liudongdong3@huawei.com/
Link: https://lore.kernel.org/r/b45e46fd8a6aa6930aaac9d7718c2e4b787a4e5e.1595935071.git.lukas@wunner.deReported-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Reported-by: Dongdong Liu <liudongdong3@huawei.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>