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Subject[RFC][PATCH 2/5] usb: dwc2: Workaround case where GOTGCTL state is wrong
Date
When removing a USB-A to USB-otg adapter cable, we get a change
status irq, and then in dwc2_conn_id_status_change, we
erroniously see the GOTGCTL_CONID_B flag set. This causes us to
get stuck in the "while (!dwc2_is_device_mode(hsotg))" loop,
spitting out "Waiting for Peripheral Mode, Mode=Host" warnings
until it fails out many seconds later.

This patch works around the issue by re-reading the GOTGCTL
state to check if the GOTGCTL_CONID_B is still set and if not
restarting the change status logic.

I suspect this isn't the best solution, but it seems to work
well for me.

Feedback would be greatly appreciated!

Cc: Wei Xu <xuwei5@hisilicon.com>
Cc: Guodong Xu <guodong.xu@linaro.org>
Cc: Amit Pundir <amit.pundir@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: John Youn <johnyoun@synopsys.com>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Chen Yu <chenyu56@huawei.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
drivers/usb/dwc2/hcd.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index df5a065..a3f34dd 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -3199,7 +3199,7 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
dev_dbg(hsotg->dev, "gotgctl=%0x\n", gotgctl);
dev_dbg(hsotg->dev, "gotgctl.b.conidsts=%d\n",
!!(gotgctl & GOTGCTL_CONID_B));
-
+again:
/* B-Device connector (Device Mode) */
if (gotgctl & GOTGCTL_CONID_B) {
/* Wait for switch to device mode */
@@ -3210,6 +3210,9 @@ static void dwc2_conn_id_status_change(struct work_struct *work)
dwc2_is_host_mode(hsotg) ? "Host" :
"Peripheral");
usleep_range(20000, 40000);
+ gotgctl = dwc2_readl(hsotg->regs + GOTGCTL);
+ if (!(gotgctl & GOTGCTL_CONID_B))
+ goto again;
if (++count > 250)
break;
}
--
2.7.4
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