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PCI: Add debug print for device ready delay

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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>
This commit is contained in:
Ido Schimmel 2023-11-15 13:17:17 +01:00 committed by David S. Miller
parent 3ed48c80b2
commit 0a5ef95923
1 changed files with 3 additions and 0 deletions
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3
drivers/pci/pci.c
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@ -1219,6 +1219,9 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
if (delay > PCI_RESET_WAIT)
pci_info(dev, "ready %dms after %s\n", delay - 1,
reset_type);
else
pci_dbg(dev, "ready %dms after %s\n", delay - 1,
reset_type);
return 0;
}