Contrary to the datasheet, setting both DETACH and PULLD_DIS bits to 1
does not always drive the DP and DM lines to high-impedance. This
prevents the host from reliably detecting a USB disconnect and subsequent
reconnect.
The symptom is that the first gadget command (e.g., dhcp) succeeds, while
subsequent commands (e.g., nfs) fail.
Disabling and re-enabling the controller entirely, instead of toggling the
PULLD_DIS bit, reliably generates a disconnect event.
The Linux driver works correctly because gadget_disconnect/gadget_connect
are always followed by gadget_udc_start/gadget_udc_stop. In U-Boot
pullup() is used solely.
This behavior has been observed on the SAM9X60-Curiosity and
AT91SAM9G25-EK boards and has been reported to Microchip.
Signed-off-by: Zixun LI <ad...@hifiphile.com>
---
drivers/usb/gadget/atmel_usba_udc.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/drivers/usb/gadget/atmel_usba_udc.c
b/drivers/usb/gadget/atmel_usba_udc.c
index
f9326f0a7e7d913bcf201ba3e4aeca9a099e7be7..a38e70957402fb3ade3de611d73e29b990d00703
100644
--- a/drivers/usb/gadget/atmel_usba_udc.c
+++ b/drivers/usb/gadget/atmel_usba_udc.c
@@ -521,16 +521,11 @@ usba_udc_set_selfpowered(struct usb_gadget *gadget, int
is_selfpowered)
static int usba_udc_pullup(struct usb_gadget *gadget, int is_on)
{
struct usba_udc *udc = to_usba_udc(gadget);
- u32 ctrl;
-
- ctrl = usba_readl(udc, CTRL);
if (is_on)
- ctrl &= ~USBA_DETACH;
+ usba_writel(udc, CTRL, USBA_ENABLE_MASK);
else
- ctrl |= USBA_DETACH;
-
- usba_writel(udc, CTRL, ctrl);
+ usba_writel(udc, CTRL, USBA_DISABLE_MASK);
return 0;
}
---
base-commit: 4d3b5c679bc9d5c6cbbeedcc1e4a186f1cc35541
change-id: 20250602-pullup-83c5540db5cd
Best regards,
--
Zixun LI <ad...@hifiphile.com>
