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From: Nicolas Ferre <nicolas.ferre@microchip•com>
To: <linux-kernel@vger•kernel.org>,
	<linux-arm-kernel@lists•infradead.org>,
	<stern@rowland•harvard.edu>, <gregkh@linuxfoundation•org>
Cc: Boris.Krasnovskiy@lairdconnect•com,
	Alexandre Belloni <alexandre.belloni@bootlin•com>,
	linux-usb@vger•kernel.org,
	Ludovic Desroches <ludovic.desroches@microchip•com>
Subject: [PATCH 2/3] USB: host: ohci-at91: suspend: delay needed before to stop clocks
Date: Wed, 11 Sep 2019 08:41:53 +0200	[thread overview]
Message-ID: <20190911064154.28633-3-nicolas.ferre@microchip.com> (raw)
In-Reply-To: <20190911064154.28633-1-nicolas.ferre@microchip.com>

In order to completely remove marginal power consumption in PM suspend,
we need to let the controller settle down before being stopped.
In ohci_hcd_at91_drv_suspend() function, one additional delay is needed before
to stop the clocks.

Reported-by: Boris Krasnovskiy <Boris.Krasnovskiy@lairdconnect•com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip•com>
---
 drivers/usb/host/ohci-at91.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
index cb63bcd5049a..85d67fe42d59 100644
--- a/drivers/usb/host/ohci-at91.c
+++ b/drivers/usb/host/ohci-at91.c
@@ -628,6 +628,7 @@ ohci_hcd_at91_drv_suspend(struct device *dev)
 
 		/* flush the writes */
 		(void) ohci_readl (ohci, &ohci->regs->control);
+		msleep(1);
 		at91_stop_clock(ohci_at91);
 	}
 
-- 
2.17.1


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  parent reply	other threads:[~2019-09-11  6:42 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-11  6:41 [PATCH 0/3] USB: host: ohci-at91: tailor power consumption Nicolas Ferre
2019-09-11  6:41 ` [PATCH 1/3] USB: host: ohci-at91: completely shutdown the controller in at91_stop_hc() Nicolas Ferre
2019-09-11  6:41 ` Nicolas Ferre [this message]
2019-09-11  6:41 ` [PATCH 3/3] USB: host: ohci-at91: resume: balance the clock start call Nicolas Ferre
2019-09-11 15:09 ` [PATCH 0/3] USB: host: ohci-at91: tailor power consumption Alan Stern

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