The ehci controller found in some Broadcom switches with integrated SoCs
has an issue which causes a soft lockup with large transfers like you
see when running ext4 on USB3 flash drive.
Port the fix from the Broadcom XLDK to increase the OUT_THRESHOLD to
avoid the problem.
Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
---
I don't have much data on what this change does. I can say it is needed to
avoid a soft lockup when using a USB3 Flash drive formatted has ext4 (USB2 +
ext4 is OK, USB3 + fat is OK). I presume the affected combination ends up using
larger transfers triggering the problem.
The equivalent change in the Broadcom XLDK is
if (IS_ENABLED(CONFIG_USB_EHCI_XGS_IPROC))
ehci_writel(ehci, BCM_USB_FIFO_THRESHOLD,
&ehci->regs->reserved4[6]);
This is problematic because it would unconditionally apply to all ehci
controllers whenever CONFIG_USB_EHCI_XGS_IPROC is enabled (also reserved4 only
goes to 6 so technically it's indexing off the end of the array).
I wasn't sure if I should add a new property or somehow detect the affected
host controller. I settled on using of_device_is_compatible() as that seemed
the simplest thing to do.
Changes in v2:
- move workaround to ehci_platform_reset
- cosmetic changes suggested by Alan
drivers/usb/host/ehci-platform.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/usb/host/ehci-platform.c b/drivers/usb/host/ehci-platform.c
index 006c4f6188a5..9804ffa9e67f 100644
--- a/drivers/usb/host/ehci-platform.c
+++ b/drivers/usb/host/ehci-platform.c
@@ -42,6 +42,9 @@
#define EHCI_MAX_CLKS 4
#define hcd_to_ehci_priv(h) ((struct ehci_platform_priv *)hcd_to_ehci(h)->priv)
+#define BCM_USB_FIFO_THRESHOLD 0x00800040
+#define bcm_iproc_insnreg01 hostpc[0]
+
struct ehci_platform_priv {
struct clk *clks[EHCI_MAX_CLKS];
struct reset_control *rsts;
@@ -75,6 +78,11 @@ static int ehci_platform_reset(struct usb_hcd *hcd)
if (pdata->no_io_watchdog)
ehci->need_io_watchdog = 0;
+
+ if (of_device_is_compatible(pdev->dev.of_node, "brcm,xgs-iproc-ehci"))
+ ehci_writel(ehci, BCM_USB_FIFO_THRESHOLD,
+ &ehci->regs->bcm_iproc_insnreg01);
+
return 0;
}
--
2.28.0
