PCI: rcar-host: Drop PMSR spinlock

The pmsr_lock spinlock used to be necessary to synchronize access to the
PMSR register, because that access could have been triggered from either
config space access in rcar_pcie_config_access() or an exception handler
rcar_pcie_aarch32_abort_handler().

The rcar_pcie_aarch32_abort_handler() case is no longer applicable since
commit 6e36203 ("PCI: rcar: Use PCI_SET_ERROR_RESPONSE after read
which triggered an exception"), which performs more accurate, controlled
invocation of the exception, and a fixup.

This leaves rcar_pcie_config_access() as the only call site from which
rcar_pcie_wakeup() is called. The rcar_pcie_config_access() can only be
called from the controller struct pci_ops .read and .write callbacks,
and those are serialized in drivers/pci/access.c using raw spinlock
'pci_lock' . It should be noted that CONFIG_PCI_LOCKLESS_CONFIG is never
set on this platform.

Since the 'pci_lock' is a raw spinlock , and the 'pmsr_lock' is not a
raw spinlock, this constellation triggers 'BUG: Invalid wait context'
with CONFIG_PROVE_RAW_LOCK_NESTING=y .

Remove the pmsr_lock to fix the locking.

Fixes: a115b1b ("PCI: rcar: Add L1 link state fix into data abort hook")
Reported-by: Duy Nguyen <[email protected]>
Reported-by: Thuan Nguyen <[email protected]>
Signed-off-by: Marek Vasut <[email protected]>
Signed-off-by: Manivannan Sadhasivam <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Cc: [email protected]
Link: https://patch.msgid.link/[email protected]

Author: Marek Vasut

drivers/pci/controller/pcie-rcar-host.c

@@ -52,20 +52,13 @@ struct rcar_pcie_host {
 	int			(*phy_init_fn)(struct rcar_pcie_host *host);
 };
 
-static DEFINE_SPINLOCK(pmsr_lock);
-
 static int rcar_pcie_wakeup(struct device *pcie_dev, void __iomem *pcie_base)
 {
-	unsigned long flags;
 	u32 pmsr, val;
 	int ret = 0;
 
-	spin_lock_irqsave(&pmsr_lock, flags);
-
-	if (!pcie_base || pm_runtime_suspended(pcie_dev)) {
-		ret = -EINVAL;
-		goto unlock_exit;
-	}
+	if (!pcie_base || pm_runtime_suspended(pcie_dev))
+		return -EINVAL;
 
 	pmsr = readl(pcie_base + PMSR);
 
@@ -87,8 +80,6 @@ static int rcar_pcie_wakeup(struct device *pcie_dev, void __iomem *pcie_base)
 		writel(L1FAEG | PMEL1RX, pcie_base + PMSR);
 	}
 
-unlock_exit:
-	spin_unlock_irqrestore(&pmsr_lock, flags);
 	return ret;
 }