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From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Wim Van Sebroeck <wim@iguana.be>,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	Wenyou.Yang@microchip.com, linux-watchdog@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Alexandre Belloni <alexandre.belloni@free-electrons.com>
Subject: [PATCH 4/4] watchdog: sama5d4: Add comment explaining what happens on resume
Date: Thu,  2 Mar 2017 18:31:14 +0100	[thread overview]
Message-ID: <20170302173114.28508-5-alexandre.belloni@free-electrons.com> (raw)
In-Reply-To: <20170302173114.28508-1-alexandre.belloni@free-electrons.com>

Because suspending to RAM may lose the register values, they are restored
on resume. This is currently done unconditionally because there is
currently no way to know (from the driver) whether they have really been
lost or are still valid. Writing MR also pings the watchdog and this may
not be what is expected so add a comment explaining why it happens.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
 drivers/watchdog/sama5d4_wdt.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index d710014f3b7d..0ae947c3d7bc 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -300,6 +300,11 @@ static int sama5d4_wdt_resume(struct device *dev)
 {
 	struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
 
+	/*
+	 * FIXME: writing MR also pings the watchdog which may not be desired.
+	 * This should only be done when the registers are lost on suspend but
+	 * there is no way to get this information right now.
+	 */
 	sama5d4_wdt_init(wdt);
 
 	return 0;
-- 
2.11.0

WARNING: multiple messages have this Message-ID (diff)
From: alexandre.belloni@free-electrons.com (Alexandre Belloni)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 4/4] watchdog: sama5d4: Add comment explaining what happens on resume
Date: Thu,  2 Mar 2017 18:31:14 +0100	[thread overview]
Message-ID: <20170302173114.28508-5-alexandre.belloni@free-electrons.com> (raw)
In-Reply-To: <20170302173114.28508-1-alexandre.belloni@free-electrons.com>

Because suspending to RAM may lose the register values, they are restored
on resume. This is currently done unconditionally because there is
currently no way to know (from the driver) whether they have really been
lost or are still valid. Writing MR also pings the watchdog and this may
not be what is expected so add a comment explaining why it happens.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
 drivers/watchdog/sama5d4_wdt.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index d710014f3b7d..0ae947c3d7bc 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -300,6 +300,11 @@ static int sama5d4_wdt_resume(struct device *dev)
 {
 	struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
 
+	/*
+	 * FIXME: writing MR also pings the watchdog which may not be desired.
+	 * This should only be done when the registers are lost on suspend but
+	 * there is no way to get this information right now.
+	 */
 	sama5d4_wdt_init(wdt);
 
 	return 0;
-- 
2.11.0

  parent reply	other threads:[~2017-03-03  8:19 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-02 17:31 [PATCH 0/4] watchdog: sama5d4: fix issues Alexandre Belloni
2017-03-02 17:31 ` Alexandre Belloni
2017-03-02 17:31 ` [PATCH 1/4] watchdog: sama5d4: fix WDDIS handling Alexandre Belloni
2017-03-02 17:31   ` Alexandre Belloni
2017-03-04 15:04   ` Guenter Roeck
2017-03-04 15:04     ` Guenter Roeck
2017-03-07  2:05   ` Wenyou.Yang
2017-03-07  2:05     ` Wenyou.Yang at microchip.com
2017-03-02 17:31 ` [PATCH 2/4] watchdog: sama5d4: fix race condition Alexandre Belloni
2017-03-02 17:31   ` Alexandre Belloni
2017-03-02 17:42   ` Guenter Roeck
2017-03-02 17:42     ` Guenter Roeck
2017-03-02 17:54     ` Alexandre Belloni
2017-03-02 17:54       ` Alexandre Belloni
2017-03-04 15:05   ` Guenter Roeck
2017-03-04 15:05     ` Guenter Roeck
2017-03-07  2:06   ` Wenyou.Yang
2017-03-07  2:06     ` Wenyou.Yang at microchip.com
2017-03-02 17:31 ` [PATCH 3/4] watchodg: sama5d4: simplify probe Alexandre Belloni
2017-03-02 17:31   ` Alexandre Belloni
2017-03-02 19:29   ` Alexander Dahl
2017-03-02 19:29     ` Alexander Dahl
2017-03-03  8:03   ` Thomas Petazzoni
2017-03-03  8:03     ` Thomas Petazzoni
2017-03-03  9:29     ` Alexandre Belloni
2017-03-03  9:29       ` Alexandre Belloni
2017-03-03 14:14       ` Guenter Roeck
2017-03-03 14:14         ` Guenter Roeck
2017-03-04 15:06   ` Guenter Roeck
2017-03-04 15:06     ` Guenter Roeck
2017-03-02 17:31 ` Alexandre Belloni [this message]
2017-03-02 17:31   ` [PATCH 4/4] watchdog: sama5d4: Add comment explaining what happens on resume Alexandre Belloni
2017-03-04 15:07   ` Guenter Roeck
2017-03-04 15:07     ` Guenter Roeck

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