[PATCH next] PCI: imx6: Add error handling in imx_pcie_cpu_addr_fixup()

[Riyan Dhiman <riyandhiman14@gmail.com>]

Added error handling to the imx_pcie_cpu_addr_fixup function for cases
where the memory window retrieval fails. The initial implementation did
not have error handling, and the function simply returned cpu_addr without
checking for failure conditions.

I have added -0ULL as a error return code but what should be the ideal return
code for error handling in this function, given the u64 return type? Common
approaches include returning ~0ULL or another invalid address value, but
clarification on best practices would be appreciated.

Signed-off-by: Riyan Dhiman <riyandhiman14@gmail.com>
---
Compile tested only. I am new to the PCI subsystem and not sure how to test these 
modules. Do I need dedicated hardware, or is there another way to test these changes?

 drivers/pci/controller/dwc/pci-imx6.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 0dbc333adcff..6af39852d2c2 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1023,6 +1023,10 @@ static u64 imx_pcie_cpu_addr_fixup(struct dw_pcie *pcie, u64 cpu_addr)
 		return cpu_addr;
 
 	entry = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
+	if(!entry) {
+		dev_err(pcie->dev, "Unable to get memory window.");
+		return -0ULL;
+	}
 	offset = entry->offset;
 
 	return (cpu_addr - offset);
-- 
2.46.0