linux-kernel - [PATCH v6] usb: ohci: disable start-of-frame interrupt in ohci_rh

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Date:   Wed, 13 Oct 2021 11:32:08 +0800
From:   Yinbo Zhu <zhuyinbo@...ngson.cn>
To:     Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <greg@...ah.com>,
        Patchwork Bot <patchwork-bot@...nel.org>
Cc:     zhuyinbo@...ngson.cn
Subject: [PATCH v6] usb: ohci: disable start-of-frame interrupt in ohci_rh_suspend

While going into S3 or S4 suspend, an OHCI host controller can
generate interrupt requests if the INTR_SF enable flag is set.  The
interrupt handler routine isn't prepared for this and it doesn't turn
off the flag, causing an interrupt storm.

To fix this problem, make ohci_rh_suspend() always disable INTR_SF
interrupts after processing the done list and the ED unlinks but
before the controller goes into the suspended (non-UsbOperational)
state.  There's no reason to leave the flag enabled, since a
suspended controller doesn't generate Start-of-Frame packets.

Signed-off-by: Yinbo Zhu <zhuyinbo@...ngson.cn>
---
Change in v6:
		1. Rework the commit log information.
		2. Move the key change code after ohci_work in 
		   ohci_rh_suspend.

 drivers/usb/host/ohci-hub.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c
index f474f2f..90cee19 100644
--- a/drivers/usb/host/ohci-hub.c
+++ b/drivers/usb/host/ohci-hub.c
@@ -91,6 +91,9 @@ static int ohci_rh_suspend (struct ohci_hcd *ohci, int autostop)
 	update_done_list(ohci);
 	ohci_work(ohci);

+	/* All ED unlinks should be finished, no need for SOF interrupts */
+	ohci_writel(ohci, OHCI_INTR_SF, &ohci->regs->intrdisable);
+
 	/*
 	 * Some controllers don't handle "global" suspend properly if
 	 * there are unsuspended ports.  For these controllers, put all
-- 
1.8.3.1