linux-stable.git/drivers/pci, branch v6.6.63 Linux kernel stable tree PCI: Mark Creative Labs EMU20k2 INTx masking as broken 2024-10-17T13:24:17+00:00 Alex Williamson alex.williamson@redhat.com 2024-09-12T21:53:27+00:00 8f53f6f96678c641a28cb1f0006387147f4eb614 [ Upstream commit 2910306655a7072640021563ec9501bfa67f0cb1 ] Per user reports, the Creative Labs EMU20k2 (Sound Blaster X-Fi Titanium Series) generates spurious interrupts when used with vfio-pci unless DisINTx masking support is disabled. Thus, quirk the device to mark INTx masking as broken. Closes: https://lore.kernel.org/all/VI1PR10MB8207C507DB5420AB4C7281E0DB9A2@VI1PR10MB8207.EURPRD10.PROD.OUTLOOK.COM Link: https://lore.kernel.org/linux-pci/20240912215331.839220-1-alex.williamson@redhat.com Reported-by: zdravko delineshev <delineshev@outlook.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> [kwilczynski: commit log] Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2910306655a7072640021563ec9501bfa67f0cb1 ]

Per user reports, the Creative Labs EMU20k2 (Sound Blaster X-Fi
Titanium Series) generates spurious interrupts when used with
vfio-pci unless DisINTx masking support is disabled.

Thus, quirk the device to mark INTx masking as broken.

Closes: https://lore.kernel.org/all/VI1PR10MB8207C507DB5420AB4C7281E0DB9A2@VI1PR10MB8207.EURPRD10.PROD.OUTLOOK.COM
Link: https://lore.kernel.org/linux-pci/20240912215331.839220-1-alex.williamson@redhat.com
Reported-by: zdravko delineshev <delineshev@outlook.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
PCI: Add ACS quirk for Qualcomm SA8775P 2024-10-17T13:24:17+00:00 Subramanian Ananthanarayanan quic_skananth@quicinc.com 2024-09-06T05:22:27+00:00 2488685858eda4a942a09c7b455fc6830d980290 [ Upstream commit 026f84d3fa62d215b11cbeb5a5d97df941e93b5c ] The Qualcomm SA8775P root ports don't advertise an ACS capability, but they do provide ACS-like features to disable peer transactions and validate bus numbers in requests. Thus, add an ACS quirk for the SA8775P. Link: https://lore.kernel.org/linux-pci/20240906052228.1829485-1-quic_skananth@quicinc.com Signed-off-by: Subramanian Ananthanarayanan <quic_skananth@quicinc.com> Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 026f84d3fa62d215b11cbeb5a5d97df941e93b5c ]

The Qualcomm SA8775P root ports don't advertise an ACS capability, but they
do provide ACS-like features to disable peer transactions and validate bus
numbers in requests.

Thus, add an ACS quirk for the SA8775P.

Link: https://lore.kernel.org/linux-pci/20240906052228.1829485-1-quic_skananth@quicinc.com
Signed-off-by: Subramanian Ananthanarayanan <quic_skananth@quicinc.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
PCI: Add function 0 DMA alias quirk for Glenfly Arise chip 2024-10-17T13:24:16+00:00 WangYuli wangyuli@uniontech.com 2024-08-23T09:57:08+00:00 bd9a77a930498f2ec677230ea0da2e3173d42c7a [ Upstream commit 9246b487ab3c3b5993aae7552b7a4c541cc14a49 ] Add DMA support for audio function of Glenfly Arise chip, which uses Requester ID of function 0. Link: https://lore.kernel.org/r/CA2BBD087345B6D1+20240823095708.3237375-1-wangyuli@uniontech.com Signed-off-by: SiyuLi <siyuli@glenfly.com> Signed-off-by: WangYuli <wangyuli@uniontech.com> [bhelgaas: lower-case hex to match local code, drop unused Device IDs] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 9246b487ab3c3b5993aae7552b7a4c541cc14a49 ]

Add DMA support for audio function of Glenfly Arise chip, which uses
Requester ID of function 0.

Link: https://lore.kernel.org/r/CA2BBD087345B6D1+20240823095708.3237375-1-wangyuli@uniontech.com
Signed-off-by: SiyuLi <siyuli@glenfly.com>
Signed-off-by: WangYuli <wangyuli@uniontech.com>
[bhelgaas: lower-case hex to match local code, drop unused Device IDs]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
bus: mhi: ep: Rename read_from_host() and write_to_host() APIs 2024-10-17T13:24:09+00:00 Manivannan Sadhasivam manivannan.sadhasivam@linaro.org 2023-11-27T08:27:37+00:00 efdfa92a823a56b9a9fb4e9e9168c69b6db3b3b4 [ Upstream commit 927105244f8bc48e6841826a5644c6a961e03b5d ] In the preparation for adding async API support, let's rename the existing APIs to read_sync() and write_sync() to make it explicit that these APIs are used for synchronous read/write. Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Stable-dep-of: c7d0b2db5bc5 ("bus: mhi: ep: Do not allocate memory for MHI objects from DMA zone") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 927105244f8bc48e6841826a5644c6a961e03b5d ]

In the preparation for adding async API support, let's rename the existing
APIs to read_sync() and write_sync() to make it explicit that these APIs
are used for synchronous read/write.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Stable-dep-of: c7d0b2db5bc5 ("bus: mhi: ep: Do not allocate memory for MHI objects from DMA zone")
Signed-off-by: Sasha Levin <sashal@kernel.org>
PCI: xilinx-nwl: Fix off-by-one in INTx IRQ handler 2024-10-04T14:29:45+00:00 Sean Anderson sean.anderson@linux.dev 2024-05-31T16:13:32+00:00 02a370c4fc0f1b70ca32302d6689a708c0dac781 commit 0199d2f2bd8cd97b310f7ed82a067247d7456029 upstream. MSGF_LEG_MASK is laid out with INTA in bit 0, INTB in bit 1, INTC in bit 2, and INTD in bit 3. Hardware IRQ numbers start at 0, and we register PCI_NUM_INTX IRQs. So to enable INTA (aka hwirq 0) we should set bit 0. Remove the subtraction of one. This bug would cause INTx interrupts not to be delivered, as enabling INTB would actually enable INTA, and enabling INTA wouldn't enable anything at all. It is likely that this got overlooked for so long since most PCIe hardware uses MSIs. This fixes the following UBSAN error: UBSAN: shift-out-of-bounds in ../drivers/pci/controller/pcie-xilinx-nwl.c:389:11 shift exponent 18446744073709551615 is too large for 32-bit type 'int' CPU: 1 PID: 61 Comm: kworker/u10:1 Not tainted 6.6.20+ #268 Hardware name: xlnx,zynqmp (DT) Workqueue: events_unbound deferred_probe_work_func Call trace: dump_backtrace (arch/arm64/kernel/stacktrace.c:235) show_stack (arch/arm64/kernel/stacktrace.c:242) dump_stack_lvl (lib/dump_stack.c:107) dump_stack (lib/dump_stack.c:114) __ubsan_handle_shift_out_of_bounds (lib/ubsan.c:218 lib/ubsan.c:387) nwl_unmask_leg_irq (drivers/pci/controller/pcie-xilinx-nwl.c:389 (discriminator 1)) irq_enable (kernel/irq/internals.h:234 kernel/irq/chip.c:170 kernel/irq/chip.c:439 kernel/irq/chip.c:432 kernel/irq/chip.c:345) __irq_startup (kernel/irq/internals.h:239 kernel/irq/chip.c:180 kernel/irq/chip.c:250) irq_startup (kernel/irq/chip.c:270) __setup_irq (kernel/irq/manage.c:1800) request_threaded_irq (kernel/irq/manage.c:2206) pcie_pme_probe (include/linux/interrupt.h:168 drivers/pci/pcie/pme.c:348) Fixes: 9a181e1093af ("PCI: xilinx-nwl: Modify IRQ chip for legacy interrupts") Link: https://lore.kernel.org/r/20240531161337.864994-3-sean.anderson@linux.dev Signed-off-by: Sean Anderson <sean.anderson@linux.dev> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 0199d2f2bd8cd97b310f7ed82a067247d7456029 upstream.

MSGF_LEG_MASK is laid out with INTA in bit 0, INTB in bit 1, INTC in bit 2,
and INTD in bit 3. Hardware IRQ numbers start at 0, and we register
PCI_NUM_INTX IRQs. So to enable INTA (aka hwirq 0) we should set bit 0.
Remove the subtraction of one.

This bug would cause INTx interrupts not to be delivered, as enabling INTB
would actually enable INTA, and enabling INTA wouldn't enable anything at
all. It is likely that this got overlooked for so long since most PCIe
hardware uses MSIs. This fixes the following UBSAN error:

  UBSAN: shift-out-of-bounds in ../drivers/pci/controller/pcie-xilinx-nwl.c:389:11
  shift exponent 18446744073709551615 is too large for 32-bit type 'int'
  CPU: 1 PID: 61 Comm: kworker/u10:1 Not tainted 6.6.20+ #268
  Hardware name: xlnx,zynqmp (DT)
  Workqueue: events_unbound deferred_probe_work_func
  Call trace:
  dump_backtrace (arch/arm64/kernel/stacktrace.c:235)
  show_stack (arch/arm64/kernel/stacktrace.c:242)
  dump_stack_lvl (lib/dump_stack.c:107)
  dump_stack (lib/dump_stack.c:114)
  __ubsan_handle_shift_out_of_bounds (lib/ubsan.c:218 lib/ubsan.c:387)
  nwl_unmask_leg_irq (drivers/pci/controller/pcie-xilinx-nwl.c:389 (discriminator 1))
  irq_enable (kernel/irq/internals.h:234 kernel/irq/chip.c:170 kernel/irq/chip.c:439 kernel/irq/chip.c:432 kernel/irq/chip.c:345)
  __irq_startup (kernel/irq/internals.h:239 kernel/irq/chip.c:180 kernel/irq/chip.c:250)
  irq_startup (kernel/irq/chip.c:270)
  __setup_irq (kernel/irq/manage.c:1800)
  request_threaded_irq (kernel/irq/manage.c:2206)
  pcie_pme_probe (include/linux/interrupt.h:168 drivers/pci/pcie/pme.c:348)

Fixes: 9a181e1093af ("PCI: xilinx-nwl: Modify IRQ chip for legacy interrupts")
Link: https://lore.kernel.org/r/20240531161337.864994-3-sean.anderson@linux.dev
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PCI: Use an error code with PCIe failed link retraining 2024-10-04T14:29:45+00:00 Maciej W. Rozycki macro@orcam.me.uk 2024-08-09T13:25:02+00:00 3d8573abdc65edd367d25df159f6be82d9b7acbf commit 59100eb248c0b15585affa546c7f6834b30eb5a4 upstream. Given how the call place in pcie_wait_for_link_delay() got structured now, and that pcie_retrain_link() returns a potentially useful error code, convert pcie_failed_link_retrain() to return an error code rather than a boolean status, fixing handling at the call site mentioned. Update the other call site accordingly. Fixes: 1abb47390350 ("Merge branch 'pci/enumeration'") Link: https://lore.kernel.org/r/alpine.DEB.2.21.2408091156530.61955@angie.orcam.me.uk Reported-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/aa2d1c4e-9961-d54a-00c7-ddf8e858a9b0@linux.intel.com/ Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Cc: <stable@vger.kernel.org> # v6.5+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 59100eb248c0b15585affa546c7f6834b30eb5a4 upstream.

Given how the call place in pcie_wait_for_link_delay() got structured now,
and that pcie_retrain_link() returns a potentially useful error code,
convert pcie_failed_link_retrain() to return an error code rather than a
boolean status, fixing handling at the call site mentioned.  Update the
other call site accordingly.

Fixes: 1abb47390350 ("Merge branch 'pci/enumeration'")
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2408091156530.61955@angie.orcam.me.uk
Reported-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/aa2d1c4e-9961-d54a-00c7-ddf8e858a9b0@linux.intel.com/
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: <stable@vger.kernel.org> # v6.5+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PCI: Correct error reporting with PCIe failed link retraining 2024-10-04T14:29:45+00:00 Maciej W. Rozycki macro@orcam.me.uk 2024-08-09T13:24:56+00:00 a200897dc704164fabdcea8205334f5cbb97051f commit 712e49c967064a3a7a5738c6f65ac540a3f6a1df upstream. Only return successful completion status from pcie_failed_link_retrain() if retraining has actually been done, preventing excessive delays from being triggered at call sites in a hope that communication will finally be established with the downstream device where in fact nothing has been done about the link in question that would justify such a hope. Fixes: a89c82249c37 ("PCI: Work around PCIe link training failures") Link: https://lore.kernel.org/r/alpine.DEB.2.21.2408091133260.61955@angie.orcam.me.uk Reported-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/aa2d1c4e-9961-d54a-00c7-ddf8e858a9b0@linux.intel.com/ Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Cc: <stable@vger.kernel.org> # v6.5+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 712e49c967064a3a7a5738c6f65ac540a3f6a1df upstream.

Only return successful completion status from pcie_failed_link_retrain() if
retraining has actually been done, preventing excessive delays from being
triggered at call sites in a hope that communication will finally be
established with the downstream device where in fact nothing has been done
about the link in question that would justify such a hope.

Fixes: a89c82249c37 ("PCI: Work around PCIe link training failures")
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2408091133260.61955@angie.orcam.me.uk
Reported-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/aa2d1c4e-9961-d54a-00c7-ddf8e858a9b0@linux.intel.com/
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: <stable@vger.kernel.org> # v6.5+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PCI: imx6: Fix missing call to phy_power_off() in error handling 2024-10-04T14:29:44+00:00 Frank Li Frank.Li@nxp.com 2024-07-29T20:18:10+00:00 f23785c6e7d30c941e5844c370f58169b518fd49 commit 5b04d44d5c74e4d8aab1678496b84700b4b343fe upstream. Fix missing call to phy_power_off() in the error path of imx6_pcie_host_init(). Remove unnecessary check for imx6_pcie->phy as the PHY API already handles NULL pointers. Fixes: cbcf8722b523 ("phy: freescale: imx8m-pcie: Fix the wrong order of phy_init() and phy_power_on()") Link: https://lore.kernel.org/linux-pci/20240729-pci2_upstream-v8-3-b68ee5ef2b4d@nxp.com Signed-off-by: Frank Li <Frank.Li@nxp.com> [kwilczynski: commit log] Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Cc: <stable@vger.kernel.org> # 6.1+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 5b04d44d5c74e4d8aab1678496b84700b4b343fe upstream.

Fix missing call to phy_power_off() in the error path of
imx6_pcie_host_init(). Remove unnecessary check for imx6_pcie->phy
as the PHY API already handles NULL pointers.

Fixes: cbcf8722b523 ("phy: freescale: imx8m-pcie: Fix the wrong order of phy_init() and phy_power_on()")
Link: https://lore.kernel.org/linux-pci/20240729-pci2_upstream-v8-3-b68ee5ef2b4d@nxp.com
Signed-off-by: Frank Li <Frank.Li@nxp.com>
[kwilczynski: commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: <stable@vger.kernel.org> # 6.1+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PCI: dra7xx: Fix threaded IRQ request for "dra7xx-pcie-main" IRQ 2024-10-04T14:29:44+00:00 Siddharth Vadapalli s-vadapalli@ti.com 2024-08-27T12:24:21+00:00 b91d041e0756590fe5cdd9b2ec81f34ae5c024fc commit 03f84b3baba7836bdfc162c19288d5ce1aa92890 upstream. Commit da87d35a6e51 ("PCI: dra7xx: Use threaded IRQ handler for "dra7xx-pcie-main" IRQ") switched from devm_request_irq() to devm_request_threaded_irq() for the "dra7xx-pcie-main" interrupt. Since the primary handler was set to NULL, the "IRQF_ONESHOT" flag should have also been set. Fix this. Fixes: da87d35a6e51 ("PCI: dra7xx: Use threaded IRQ handler for "dra7xx-pcie-main" IRQ") Suggested-by: Vignesh Raghavendra <vigneshr@ti.com> Link: https://lore.kernel.org/linux-pci/20240827122422.985547-2-s-vadapalli@ti.com Reported-by: Udit Kumar <u-kumar1@ti.com> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com> Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Reviewed-by: Kevin Hilman <khilman@baylibre.com> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 03f84b3baba7836bdfc162c19288d5ce1aa92890 upstream.

Commit da87d35a6e51 ("PCI: dra7xx: Use threaded IRQ handler for
"dra7xx-pcie-main" IRQ") switched from devm_request_irq() to
devm_request_threaded_irq() for the "dra7xx-pcie-main" interrupt.

Since the primary handler was set to NULL, the "IRQF_ONESHOT" flag
should have also been set. Fix this.

Fixes: da87d35a6e51 ("PCI: dra7xx: Use threaded IRQ handler for "dra7xx-pcie-main" IRQ")
Suggested-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/linux-pci/20240827122422.985547-2-s-vadapalli@ti.com
Reported-by: Udit Kumar <u-kumar1@ti.com>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PCI: Clear the LBMS bit after a link retrain 2024-10-04T14:29:44+00:00 Maciej W. Rozycki macro@orcam.me.uk 2024-08-09T13:24:46+00:00 894f21117f638f9afc6021c383c751dc96b6e138 commit 8037ac08c2bbb3186f83a5a924f52d1048dbaec5 upstream. The LBMS bit, where implemented, is set by hardware either in response to the completion of retraining caused by writing 1 to the Retrain Link bit or whenever hardware has changed the link speed or width in attempt to correct unreliable link operation. It is never cleared by hardware other than by software writing 1 to the bit position in the Link Status register and we never do such a write. We currently have two places, namely apply_bad_link_workaround() and pcie_failed_link_retrain() in drivers/pci/controller/dwc/pcie-tegra194.c and drivers/pci/quirks.c respectively where we check the state of the LBMS bit and neither is interested in the state of the bit resulting from the completion of retraining, both check for a link fault. And in particular pcie_failed_link_retrain() causes issues consequently, by trying to retrain a link where there's no downstream device anymore and the state of 1 in the LBMS bit has been retained from when there was a device downstream that has since been removed. Clear the LBMS bit then at the conclusion of pcie_retrain_link(), so that we have a single place that controls it and that our code can track link speed or width changes resulting from unreliable link operation. Fixes: a89c82249c37 ("PCI: Work around PCIe link training failures") Link: https://lore.kernel.org/r/alpine.DEB.2.21.2408091133140.61955@angie.orcam.me.uk Reported-by: Matthew W Carlis <mattc@purestorage.com> Link: https://lore.kernel.org/r/20240806000659.30859-1-mattc@purestorage.com/ Link: https://lore.kernel.org/r/20240722193407.23255-1-mattc@purestorage.com/ Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org> Cc: <stable@vger.kernel.org> # v6.5+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8037ac08c2bbb3186f83a5a924f52d1048dbaec5 upstream.

The LBMS bit, where implemented, is set by hardware either in response
to the completion of retraining caused by writing 1 to the Retrain Link
bit or whenever hardware has changed the link speed or width in attempt
to correct unreliable link operation.  It is never cleared by hardware
other than by software writing 1 to the bit position in the Link Status
register and we never do such a write.

We currently have two places, namely apply_bad_link_workaround() and
pcie_failed_link_retrain() in drivers/pci/controller/dwc/pcie-tegra194.c
and drivers/pci/quirks.c respectively where we check the state of the LBMS
bit and neither is interested in the state of the bit resulting from the
completion of retraining, both check for a link fault.

And in particular pcie_failed_link_retrain() causes issues consequently, by
trying to retrain a link where there's no downstream device anymore and the
state of 1 in the LBMS bit has been retained from when there was a device
downstream that has since been removed.

Clear the LBMS bit then at the conclusion of pcie_retrain_link(), so that
we have a single place that controls it and that our code can track link
speed or width changes resulting from unreliable link operation.

Fixes: a89c82249c37 ("PCI: Work around PCIe link training failures")
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2408091133140.61955@angie.orcam.me.uk
Reported-by: Matthew W Carlis <mattc@purestorage.com>
Link: https://lore.kernel.org/r/20240806000659.30859-1-mattc@purestorage.com/
Link: https://lore.kernel.org/r/20240722193407.23255-1-mattc@purestorage.com/
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Cc: <stable@vger.kernel.org> # v6.5+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>