PCI: Wait for device readiness after D3hot -> D0uninitialized transition

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For a device that advertises No_Soft_Reset == 0, a transition from D3hot to
D0uninitialized is a soft reset, and the resulting internal device state is
undefined.

Per PCIe r7.0, sec 2.3.1, a transition from D3hot to D0uninitialized
mandates a minimum 10 ms delay before accessing the device. Following this
delay, the device is permitted to respond to initial configuration requests
with a Request Retry Status (RRS) completion status if it needs more time
to initialize.

Call pci_dev_wait() after pci_power_up() performs a D3hot->D0uninitialized
transition to ensure the device is ready to accept config accesses, as is
done after the similar transition in pci_pm_reset().

If the device is already ready, this is essentially a no-op except for one
additional config read.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Link: https://patch.msgid.link/20260518191220.636213-3-bhelgaas@google.com

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Bjorn Helgaas 2026-05-18 14:12:19 -05:00 • committed by Bjorn Helgaas

parent 6113cea475

commit 41167a1e98

1 changed files with 22 additions and 2 deletions

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drivers/pci/pci.c

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