[PATCH v2] PCI: dwc: Skip MEM outbound iATU setup for identity mappings

[Xincheng Ji]

No outbound iATU translation is required when the parent-bus address
matches the PCI address. This is a DesignWare controller property, not
an UltraRISC-specific behavior.

Compare the addresses directly and skip MEM outbound iATU setup when
they match. Remove bypass_ob_mem_iatu and the UltraRISC-specific setting.
CFG and I/O accesses, as well as non-identity-mapped MEM ranges, still
use outbound iATU windows.

Fixes: 17b478b29cf1 ("PCI: dwc: Allow drivers to skip MEM outbound iATU setup")
Fixes: 8da2b970ed4c ("PCI: ultrarisc: Skip MEM outbound iATU setup on DP1000")
Signed-off-by: Xincheng Ji <jixincheng@xxxxxxxxxxxxx>
---
This series follows up on the recently applied MEM outbound iATU support.

The DesignWare outbound no-match path does not translate addresses. Skip
MEM outbound iATU programming whenever atu.parent_bus_addr matches
atu.pci_addr, rather than relying on a driver-specific flag. CFG and I/O
accesses, as well as non-identity-mapped MEM ranges, continue to use
outbound iATU windows.

The UltraRISC DP1000 driver has removed the now-unneeded 
bypass_ob_mem_iatu, and the general DesignWare PCIe host 
code has also dropped bypass_ob_mem_iatu, directly comparing 
the parent bus and PCI addresses before setting up the MEM 
outbound iATU window
---
Changes in v2:
- Merge patch1 and patch2, because they depend on each other
- Link to v1: https://patch.msgid.link/20261019-dw-pci-fix-v1-0-9b7860f919b9@xxxxxxxxxxxxx
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 17 +++++------------
 drivers/pci/controller/dwc/pcie-designware.h      |  1 -
 drivers/pci/controller/dwc/pcie-ultrarisc.c       |  6 ------
 3 files changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index cf5ca281e91b..c593a1f1c2e0 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -918,19 +918,12 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
 		atu.parent_bus_addr = entry->res->start - pci->parent_bus_offset;
 		atu.pci_addr = entry->res->start - entry->offset;
 
-		if (pp->bypass_ob_mem_iatu) {
-			/*
-			 * The no-match pass-through path preserves the correct
-			 * PCI address only for identity-mapped MEM ranges.
-			 */
-			if (atu.parent_bus_addr != atu.pci_addr) {
-				dev_err(pci->dev,
-					"Cannot bypass outbound iATU for non-identity MEM range %pr\n",
-					entry->res);
-				return -EINVAL;
-			}
+		/*
+		 * No ATU translation is required when the parent-bus address matches
+		 * the PCI address. This is a property of the DesignWare controller.
+		 */
+		if (atu.parent_bus_addr == atu.pci_addr)
 			continue;
-		}
 
 		/* Adjust iATU size if MSG TLP region was allocated before */
 		if (pp->msg_res && pp->msg_res->parent == entry->res)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 799c05213ae3..128729fee607 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -471,7 +471,6 @@ struct dw_pcie_rp {
 	struct pci_config_window *cfg;
 	bool			ecam_enabled;
 	bool			native_ecam;
-	bool			bypass_ob_mem_iatu;
 	bool                    skip_l23_ready;
 	bool			skip_pwrctrl_off;
 	/* Set if the RC loses power during suspend */
diff --git a/drivers/pci/controller/dwc/pcie-ultrarisc.c b/drivers/pci/controller/dwc/pcie-ultrarisc.c
index 523f454c6c52..a0d328c0c09b 100644
--- a/drivers/pci/controller/dwc/pcie-ultrarisc.c
+++ b/drivers/pci/controller/dwc/pcie-ultrarisc.c
@@ -154,12 +154,6 @@ static int ultrarisc_pcie_probe(struct platform_device *pdev)
 
 	pp = &pci->pp;
 
-	/*
-	 * DP1000 routes MEM transactions without outbound iATU windows, which
-	 * avoids the 16-window/4GB-per-window aperture limit.
-	 */
-	pp->bypass_ob_mem_iatu = true;
-
 	platform_set_drvdata(pdev, ultra);
 
 	ret = ultrarisc_pcie_init_clks(ultra);

---
base-commit: 0a2602de077462d3111eb9fd3da5b12a57fc6c93
change-id: 20261015-dw-pci-fix-c8e51f83be02

Best regards,
--  
Xincheng Ji <jixincheng@xxxxxxxxxxxxx>