[PATCH v4 1/2] cxl: Set the PBCQ Tunnel BAR register when enabling capi mode

Philippe Bergheaud felix at linux.ibm.com
Mon May 14 18:27:35 AEST 2018

Skiboot used to set the default Tunnel BAR register value when capi mode
was enabled. This approach was ok for the cxl driver, but prevented other
drivers from choosing different values.

Skiboot versions > 5.11 will not set the default value any longer. This
patch modifies the cxl driver to set/reset the Tunnel BAR register when
entering/exiting the cxl mode, with pnv_pci_set_tunnel_bar().

That should work with old skiboot (since we are re-writing the value
already set) and new skiboot.

Signed-off-by: Philippe Bergheaud <felix at linux.ibm.com>
Reviewed-by: Christophe Lombard <clombard at linux.vnet.ibm.com>
Acked-by: Frederic Barrat <fbarrat at linux.vnet.ibm.com>
v2: Restrict tunnel bar setting to power9.
    Do not fail cxl_configure_adapter() on tunnel bar setting error.
    Log an info message instead, and continue configuring capi mode.

v3,v4: No change.
 drivers/misc/cxl/pci.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 83f1d08058fc..355c789406f7 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1742,6 +1742,10 @@ static int cxl_configure_adapter(struct cxl *adapter, struct pci_dev *dev)
 	/* Required for devices using CAPP DMA mode, harmless for others */
+	if (cxl_is_power9())
+		if (pnv_pci_set_tunnel_bar(dev, 0x00020000E0000000ull, 1))
+			dev_info(&dev->dev, "Tunneled operations unsupported\n");
 	if ((rc = pnv_phb_to_cxl_mode(dev, adapter->native->sl_ops->capi_mode)))
 		goto err;
@@ -1768,6 +1772,8 @@ static void cxl_deconfigure_adapter(struct cxl *adapter)
 	struct pci_dev *pdev = to_pci_dev(adapter->dev.parent);
+	if (cxl_is_power9())
+		pnv_pci_set_tunnel_bar(pdev, 0x00020000E0000000ull, 0);

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