PCI: aardvark: Update comment about link going down after link-up

Update the comment about what happens when link goes down after we have
checked for link-up. If a PIO request is done while link-down, we have
a serious problem.

Link: https://lore.kernel.org/r/20220110015018.26359-23-kabel@kernel.org
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
index 3cbaffe892a48617ff487a6068c388ca35633266..5be382b19d9a7add1f9b46fae602fc5758d1d7d2 100644 (file)
--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -998,8 +998,12 @@ static bool advk_pcie_valid_device(struct advk_pcie *pcie, struct pci_bus *bus,
                return false;
 
        /*
-        * If the link goes down after we check for link-up, nothing bad
-        * happens but the config access times out.
+        * If the link goes down after we check for link-up, we have a problem:
+        * if a PIO request is executed while link-down, the whole controller
+        * gets stuck in a non-functional state, and even after link comes up
+        * again, PIO requests won't work anymore, and a reset of the whole PCIe
+        * controller is needed. Therefore we need to prevent sending PIO
+        * requests while the link is down.
         */
        if (!pci_is_root_bus(bus) && !advk_pcie_link_up(pcie))
                return false;