From: Pali Rohár pali@kernel.org
commit 70e380250c3621c55ff218cbaf2272830d9dbb1d upstream.
When there is no PCIe card connected and advk_pcie_rd_conf() or advk_pcie_wr_conf() is called for PCI bus which doesn't belong to emulated root bridge, the aardvark driver throws the following error message:
advk-pcie d0070000.pcie: config read/write timed out
Obviously accessing PCIe registers of disconnected card is not possible.
Extend check in advk_pcie_valid_device() function for validating availability of PCIe bus. If PCIe link is down, then the device is marked as Not Found and the driver does not try to access these registers.
This is just an optimization to prevent accessing PCIe registers when card is disconnected. Trying to access PCIe registers of disconnected card does not cause any crash, kernel just needs to wait for a timeout. So if card disappear immediately after checking for PCIe link (before accessing PCIe registers), it does not cause any problems.
Link: https://lore.kernel.org/r/20200702083036.12230-1-pali@kernel.org Signed-off-by: Pali Rohár pali@kernel.org Signed-off-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Signed-off-by: Marek Behún kabel@kernel.org --- drivers/pci/controller/pci-aardvark.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index ca2d6b5534c9..25b2ec6cb26e 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -806,6 +806,13 @@ static bool advk_pcie_valid_device(struct advk_pcie *pcie, struct pci_bus *bus, if ((bus->number == pcie->root_bus_nr) && PCI_SLOT(devfn) != 0) return false;
+ /* + * If the link goes down after we check for link-up, nothing bad + * happens but the config access times out. + */ + if (bus->number != pcie->root_bus_nr && !advk_pcie_link_up(pcie)) + return false; + return true; }