host_bridge::reset_slot() is supposed to reset the PCI root port/slot. Once
that happens, the config space content would be lost. This was reported by
Niklas on the dw-rockchip based platform where the MPS setting of the root
port was lost after the host_bridge::reset_slot() callback. Hence, save the
config space before calling the host_bridge::reset_slot() callback and
restore it afterwards.
While at it, make sure that the callback is only called for root ports by
checking if the bridge is behind the root bus.
Fixes: d5c1e1c25b37 ("PCI/ERR: Add support for resetting the slots in a platform specific way")
Reported-by: Niklas Cassel <cassel@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-pci/aC9OrPAfpzB_A4K2@ryzen
Suggested-by: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
drivers/pci/pci.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 4d396bbab4a8..6d6e9ce2bbcc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4985,10 +4985,19 @@ void __weak pcibios_reset_secondary_bus(struct pci_dev *dev)
struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
int ret;
- if (host->reset_slot) {
+ if (pci_is_root_bus(dev->bus) && host->reset_slot) {
+ /*
+ * Save the config space of the root port before doing the
+ * reset, since the state could be lost. The device state
+ * should've been saved by the caller.
+ */
+ pci_save_state(dev);
ret = host->reset_slot(host, dev);
if (ret)
pci_err(dev, "failed to reset slot: %d\n", ret);
+ else
+ /* Now restore it on success */
+ pci_restore_state(dev);
return;
}
--
2.43.0
