[PATCH v4 13/25] PCI: altera: Remove redundant error fabrication when device read fails

From: Naveen Naidu
Date: Thu Nov 18 2021 - 09:07:53 EST

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error. There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

The host controller drivers sets the error response values (~0) and
returns an error when faulty hardware read occurs. But the error
response value (~0) is already being set in PCI_OP_READ and
PCI_USER_READ_CONFIG whenever a read by host controller driver fails.

Thus, it's no longer necessary for the host controller drivers to
fabricate any error response.

This helps unify PCI error response checking and make error check
consistent and easier to find.

Signed-off-by: Naveen Naidu <naveennaidu479@xxxxxxxxx>
drivers/pci/controller/pcie-altera.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/pcie-altera.c b/drivers/pci/controller/pcie-altera.c
index 2513e9363236..a6bdf9aff833 100644
--- a/drivers/pci/controller/pcie-altera.c
+++ b/drivers/pci/controller/pcie-altera.c
@@ -510,10 +510,8 @@ static int altera_pcie_cfg_read(struct pci_bus *bus, unsigned int devfn,
if (altera_pcie_hide_rc_bar(bus, devfn, where))

- if (!altera_pcie_valid_device(pcie, bus, PCI_SLOT(devfn))) {
- *value = 0xffffffff;
+ if (!altera_pcie_valid_device(pcie, bus, PCI_SLOT(devfn)))
- }

return _altera_pcie_cfg_read(pcie, bus->number, devfn, where, size,