[PATCH 1/3] usb: early: Avoid using DbC if already enabled

From: Connor Davis
Date: Tue May 11 2021 - 20:18:30 EST


Check if the debug capability is enabled in early_xdbc_parse_parameter,
and if it is, return with an error. This avoids collisions with whatever
enabled the DbC prior to linux starting.

Signed-off-by: Connor Davis <connojdavis@xxxxxxxxx>
---
drivers/usb/early/xhci-dbc.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index be4ecbabdd58..ca67fddc2d36 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -642,6 +642,16 @@ int __init early_xdbc_parse_parameter(char *s)
}
xdbc.xdbc_reg = (struct xdbc_regs __iomem *)(xdbc.xhci_base + offset);

+ if (readl(&xdbc.xdbc_reg->control) & CTRL_DBC_ENABLE) {
+ pr_notice("xhci debug capability already in use\n");
+ early_iounmap(xdbc.xhci_base, xdbc.xhci_length);
+ xdbc.xdbc_reg = NULL;
+ xdbc.xhci_base = NULL;
+ xdbc.xhci_length = 0;
+
+ return -ENODEV;
+ }
+
return 0;
}

--
2.31.1