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[RFC,v1,3/3] PCI: vmd: Add WA for VMD PCH rootbus support

Message ID 20241025150153.983306-4-szymon.durawa@linux.intel.com (mailing list archive)
State New
Headers show
Series VMD add PCH rootbus support | expand

Commit Message

Szymon Durawa Oct. 25, 2024, 3:01 p.m. UTC 
VMD PCH rootbus primary number is 0x80 and pci_scan_bridge_extend()
cannot assign it as "hard-wired to 0" and marks setup as broken. To
avoid this, PCH bus number has to be the same as PCH primary number.

Suggested-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Reviewed-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
Signed-off-by: Szymon Durawa <szymon.durawa@linux.intel.com>
---
 drivers/pci/controller/vmd.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 842b70a21325..bb47e0a76c89 100755
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -404,8 +404,22 @@  static inline u8 vmd_has_pch_rootbus(struct vmd_dev *vmd)
 static void __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
 				  unsigned int devfn, int reg, int len)
 {
-	unsigned int busnr_ecam = bus->number - vmd->busn_start[VMD_BUS_0];
-	u32 offset = PCIE_ECAM_OFFSET(busnr_ecam, devfn, reg);
+	unsigned char bus_number;
+	unsigned int busnr_ecam;
+	u32 offset;
+
+	/*
+	 * VMD WA: for PCH rootbus, bus number is set to VMD_PRIMARY_PCH_BUS
+	 * (see comment in vmd_create_pch_bus()) but original value is 0xE1
+	 * which is stored in vmd->busn_start[VMD_BUS_1].
+	 */
+	if (vmd_has_pch_rootbus(vmd) && bus->number == VMD_PRIMARY_PCH_BUS)
+		bus_number = vmd->busn_start[VMD_BUS_1];
+	else
+		bus_number = bus->number;
+
+	busnr_ecam = bus_number - vmd->busn_start[VMD_BUS_0];
+	offset = PCIE_ECAM_OFFSET(busnr_ecam, devfn, reg);
 
 	if (offset + len >= resource_size(&vmd->dev->resource[VMD_CFGBAR]))
 		return NULL;
@@ -1023,6 +1037,14 @@  static int vmd_create_pch_bus(struct vmd_dev *vmd, struct pci_sysdata *sd,
 	 */
 	vmd->bus[VMD_BUS_1]->primary = VMD_PRIMARY_PCH_BUS;
 
+	/* This is a workaround for pci_scan_bridge_extend() code.
+	 * It assigns setup as broken when primary != bus->number and
+	 * for PCH rootbus primary is not "hard-wired to 0".
+	 * To avoid this, vmd->bus[VMD_BUS_1]->number and
+	 * vmd->bus[VMD_BUS_1]->primary are updated to the same value.
+	 */
+	vmd->bus[VMD_BUS_1]->number = VMD_PRIMARY_PCH_BUS;
+
 	vmd_copy_host_bridge_flags(
 		pci_find_host_bridge(vmd->dev->bus),
 		to_pci_host_bridge(vmd->bus[VMD_BUS_1]->bridge));