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Currently, the time it took a PCI device to become ready after reset is
only printed if it was longer than 1000ms ('PCI_RESET_WAIT'). However,
for debugging purposes it is useful to know this time even if it was
shorter. For example, with the device I am working on, hardware
engineers asked to verify that it becomes ready on the first try (no
delay).
To that end, add a debug level print that can be enabled using dynamic
debug. Example:
# echo 1 > /sys/bus/pci/devices/0000\:01\:00.0/reset
# dmesg -c | grep ready
# echo "file drivers/pci/pci.c +p" > /sys/kernel/debug/dynamic_debug/control
# echo 1 > /sys/bus/pci/devices/0000\:01\:00.0/reset
# dmesg -c | grep ready
[ 396.060335] mlxsw_spectrum4 0000:01:00.0: ready 0ms after bus reset
# echo "file drivers/pci/pci.c -p" > /sys/kernel/debug/dynamic_debug/control
# echo 1 > /sys/bus/pci/devices/0000\:01\:00.0/reset
# dmesg -c | grep ready
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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.