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* [PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup
@ 2021-07-31  0:29 Wesley Cheng
  2021-08-02 21:33 ` Jack Pham
  0 siblings, 1 reply; 4+ messages in thread
From: Wesley Cheng @ 2021-07-31  0:29 UTC (permalink / raw)
  To: balbi, gregkh; +Cc: linux-usb, linux-kernel, Wesley Cheng

If the device is already in the runtime suspended state, any call to
the pullup routine will issue a runtime resume on the DWC3 core
device.  If the USB gadget is disabling the pullup, then avoid having
to issue a runtime resume, as DWC3 gadget has already been
halted/stopped.

This fixes an issue where the following condition occurs:

usb_gadget_remove_driver()
-->usb_gadget_disconnect()
 -->dwc3_gadget_pullup(0)
  -->pm_runtime_get_sync() -> ret = 0
  -->pm_runtime_put() [async]
-->usb_gadget_udc_stop()
 -->dwc3_gadget_stop()
  -->dwc->gadget_driver = NULL
...

dwc3_suspend_common()
-->dwc3_gadget_suspend()
 -->DWC3 halt/stop routine skipped, driver_data == NULL

This leads to a situation where the DWC3 gadget is not properly
stopped, as the runtime resume would have re-enabled EP0 and event
interrupts, and since we avoided the DWC3 gadget suspend, these
resources were never disabled.

Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
---
 drivers/usb/dwc3/gadget.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index a29a4ca..5d08454 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2435,6 +2435,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 	}
 
 	/*
+	 * Avoid issuing a runtime resume if the device is already in the
+	 * suspended state during gadget disconnect.  DWC3 gadget was already
+	 * halted/stopped during runtime suspend.
+	 */
+	if (!is_on) {
+		pm_runtime_barrier(dwc->dev);
+		if (pm_runtime_suspended(dwc->dev))
+			return 0;
+	}
+
+	/*
 	 * Check the return value for successful resume, or error.  For a
 	 * successful resume, the DWC3 runtime PM resume routine will handle
 	 * the run stop sequence, so avoid duplicate operations here.
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project


^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-08-04  6:19 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-31  0:29 [PATCH] usb: dwc3: gadget: Avoid runtime resume if disabling pullup Wesley Cheng
2021-08-02 21:33 ` Jack Pham
2021-08-03  7:58   ` Felipe Balbi
2021-08-04  6:19     ` Wesley Cheng

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