linux-kernel - [PATCH] usb: host: ohci-at91: suspend/resume ports after/before OHCI accesses

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Date:   Wed, 9 Jun 2021 15:10:27 +0300
From:   Claudiu Beznea <claudiu.beznea@...rochip.com>
To:     <stern@...land.harvard.edu>, <gregkh@...uxfoundation.org>,
        <nicolas.ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <ludovic.desroches@...rochip.com>, <cristian.birsan@...rochip.com>
CC:     <linux-usb@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: [PATCH] usb: host: ohci-at91: suspend/resume ports after/before OHCI accesses

On SAMA7G5 suspending ports will cut the access to OHCI registers and
any subsequent access to them will lead to CPU being blocked trying to
access that memory. Same thing happens on resume: if OHCI memory is
accessed before resuming ports the CPU will block on that access. The
OCHI memory is accessed on suspend/resume though
ohci_suspend()/ohci_resume().

Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
---

The patch was tested on SAMA7G5, SAMA5D2 and SAM9X60.

Thank you,
Claudiu Beznea

 drivers/usb/host/ohci-at91.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
index b3a6a497dcb1..7c6202b05ff4 100644
--- a/drivers/usb/host/ohci-at91.c
+++ b/drivers/usb/host/ohci-at91.c
@@ -666,8 +666,6 @@ ohci_hcd_at91_drv_suspend(struct device *dev)
 	if (ohci_at91->wakeup)
 		enable_irq_wake(hcd->irq);
 
-	ohci_at91_port_suspend(ohci_at91, 1);
-
 	ret = ohci_suspend(hcd, ohci_at91->wakeup);
 	if (ret) {
 		if (ohci_at91->wakeup)
@@ -687,7 +685,10 @@ ohci_hcd_at91_drv_suspend(struct device *dev)
 		/* flush the writes */
 		(void) ohci_readl (ohci, &ohci->regs->control);
 		msleep(1);
+		ohci_at91_port_suspend(ohci_at91, 1);
 		at91_stop_clock(ohci_at91);
+	} else {
+		ohci_at91_port_suspend(ohci_at91, 1);
 	}
 
 	return ret;
@@ -699,6 +700,8 @@ ohci_hcd_at91_drv_resume(struct device *dev)
 	struct usb_hcd	*hcd = dev_get_drvdata(dev);
 	struct ohci_at91_priv *ohci_at91 = hcd_to_ohci_at91_priv(hcd);
 
+	ohci_at91_port_suspend(ohci_at91, 0);
+
 	if (ohci_at91->wakeup)
 		disable_irq_wake(hcd->irq);
 	else
@@ -706,8 +709,6 @@ ohci_hcd_at91_drv_resume(struct device *dev)
 
 	ohci_resume(hcd, false);
 
-	ohci_at91_port_suspend(ohci_at91, 0);
-
 	return 0;
 }
 
-- 
2.25.1