linux-kernel - [PATCH 3.16 077/254] usb: musb: da8xx: fix babble condition handling

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Message-ID: <lsq.1519831218.674591392@decadent.org.uk>
Date:   Wed, 28 Feb 2018 15:20:18 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Bin Liu" <b-liu@...com>
Subject: [PATCH 3.16 077/254] usb: musb: da8xx: fix babble condition handling

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Bin Liu <b-liu@...com>

commit bd3486ded7a0c313a6575343e6c2b21d14476645 upstream.

When babble condition happens, the musb controller might automatically
turns off VBUS. On DA8xx platform, the controller generates drvvbus
interrupt for turning off VBUS along with the babble interrupt.

In this case, we should handle the babble interrupt first and recover
from the babble condition.

This change ignores the drvvbus interrupt if babble interrupt is also
generated at the same time, so the babble recovery routine works
properly.

Signed-off-by: Bin Liu <b-liu@...com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/usb/musb/da8xx.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/usb/musb/da8xx.c
+++ b/drivers/usb/musb/da8xx.c
@@ -350,7 +350,15 @@ static irqreturn_t da8xx_musb_interrupt(
 			musb->xceiv->state = OTG_STATE_A_WAIT_VRISE;
 			portstate(musb->port1_status |= USB_PORT_STAT_POWER);
 			del_timer(&otg_workaround);
-		} else {
+		} else if (!(musb->int_usb & MUSB_INTR_BABBLE)) {
+			/*
+			 * When babble condition happens, drvvbus interrupt
+			 * is also generated. Ignore this drvvbus interrupt
+			 * and let babble interrupt handler recovers the
+			 * controller; otherwise, the host-mode flag is lost
+			 * due to the MUSB_DEV_MODE() call below and babble
+			 * recovery logic will not be called.
+			 */
 			musb->is_active = 0;
 			MUSB_DEV_MODE(musb);
 			otg->default_a = 0;