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Vidya Sagar 4e708563de PCI: tegra194: Handle errors in BPMP response 
commit f8c9ad46b0 upstream.

The return value from tegra_bpmp_transfer() indicates the success or
failure of the IPC transaction with BPMP. If the transaction succeeded, we
also need to check the actual command's result code.

If we don't have error handling for tegra_bpmp_transfer(), we will set the
pcie->ep_state to EP_STATE_ENABLED even when the tegra_bpmp_transfer()
command fails. Thus, the pcie->ep_state will get out of sync with reality,
and any further PERST# assert + deassert will be a no-op and will not
trigger the hardware initialization sequence.

This is because pex_ep_event_pex_rst_deassert() checks the current
pcie->ep_state, and does nothing if the current state is already
EP_STATE_ENABLED.

Thus, it is important to have error handling for tegra_bpmp_transfer(),
such that the pcie->ep_state can not get out of sync with reality, so that
we will try to initialize the hardware not only during the first PERST#
assert + deassert, but also during any succeeding PERST# assert + deassert.

One example where this fix is needed is when using a rock5b as host.
During the initial PERST# assert + deassert (triggered by the bootloader on
the rock5b) pex_ep_event_pex_rst_deassert() will get called, but for some
unknown reason, the tegra_bpmp_transfer() call to initialize the PHY fails.
Once Linux has been loaded on the rock5b, the PCIe driver will once again
assert + deassert PERST#. However, without tegra_bpmp_transfer() error
handling, this second PERST# assert + deassert will not trigger the
hardware initialization sequence.

With tegra_bpmp_transfer() error handling, the second PERST# assert +
deassert will once again trigger the hardware to be initialized and this
time the tegra_bpmp_transfer() succeeds.

Fixes: c57247f940 ("PCI: tegra: Add support for PCIe endpoint mode in Tegra194")
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
[cassel: improve commit log]
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250922140822.519796-8-cassel@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-10-19 16:23:17 +02:00
arch xtensa: simdisk: add input size check in proc_write_simdisk 2025-10-19 16:23:15 +02:00
block blk-crypto: fix missing blktrace bio split events 2025-10-19 16:23:12 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2025-04-25 10:44:04 +02:00
crypto crypto: essiv - Check ssize for decryption and in-place encryption 2025-10-19 16:23:10 +02:00
Documentation dt-bindings: phy: rockchip-inno-csi-dphy: make power-domains non-required 2025-10-19 16:23:11 +02:00
drivers PCI: tegra194: Handle errors in BPMP response 2025-10-19 16:23:17 +02:00
fs openat2: don't trigger automounts with RESOLVE_NO_XDEV 2025-10-19 16:23:14 +02:00
include scsi: libsas: Add sas_task_find_rq() 2025-10-19 16:23:07 +02:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:23:13 +02:00
io_uring io_uring: include dying ring in task_work "should cancel" state 2025-09-25 10:58:53 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:07:30 +01:00
kernel sched/deadline: Fix race in push_dl_task() 2025-10-19 16:23:15 +02:00
lib lib/genalloc: fix device leak in of_gen_pool_get() 2025-10-19 16:23:14 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: hugetlb: avoid soft lockup when mprotect to large memory area 2025-10-15 11:56:40 +02:00
net sctp: Fix MAC comparison to be constant-time 2025-10-19 16:23:15 +02:00
rust rust: module: place cleanup_module() in .exit.text section 2025-07-06 10:57:54 +02:00
samples ftrace/samples: Fix function size computation 2025-09-19 16:29:56 +02:00
scripts gcc-plugins: Remove TODO_verify_il for GCC >= 16 2025-10-15 11:56:20 +02:00
security KEYS: trusted_tpm1: Compare HMAC values in constant time 2025-10-19 16:23:14 +02:00
sound ASoC: Intel: bytcr_rt5651: Fix invalid quirk input mapping 2025-10-15 11:56:33 +02:00
tools rseq/selftests: Use weak symbol reference, not definition, to link with glibc 2025-10-19 16:23:16 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-06-27 11:07:25 +01:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:46:21 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:21:15 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS sign-file,extract-cert: move common SSL helper functions to a header 2025-04-25 10:44:04 +02:00
Makefile Linux 6.1.156 2025-10-15 11:56:41 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.