lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 20 Oct 2014 11:04:46 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Jonathan Corbet <corbet@....net>,
	Russell King <linux@....linux.org.uk>,
	Dan Williams <dan.j.williams@...el.com>,
	Vinod Koul <vinod.koul@...el.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	linux-pm@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
	Lars-Peter Clausen <lars@...afoo.de>,
	Michal Simek <michal.simek@...inx.com>
Cc:	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: [PATCH v8 3/5] amba: Don't unprepare the clocks if device driver wants
 IRQ safe runtime PM

The AMBA bus driver defines runtime Power Management functions which
disable and unprepare AMBA bus clock. This is problematic for runtime PM
because unpreparing a clock might sleep so it is not interrupt safe.

However some drivers may want to implement runtime PM functions in
interrupt-safe way (see pm_runtime_irq_safe()). In such case the AMBA
bus driver should only disable/enable the clock in runtime suspend and
resume callbacks.

Detect the device driver behavior after calling its probe function and
store it. During runtime suspend/resume deal with clocks according to
stored value.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
---
 drivers/amba/bus.c       | 29 +++++++++++++++++++++++++----
 include/linux/amba/bus.h |  1 +
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 47bbdc1b5be3..474434e1b1b9 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -95,8 +95,18 @@ static int amba_pm_runtime_suspend(struct device *dev)
 	struct amba_device *pcdev = to_amba_device(dev);
 	int ret = pm_generic_runtime_suspend(dev);
 
-	if (ret == 0 && dev->driver)
-		clk_disable_unprepare(pcdev->pclk);
+	if (ret == 0 && dev->driver) {
+		/*
+		 * Drivers should not change pm_runtime_irq_safe()
+		 * after probe.
+		 */
+		WARN_ON(pcdev->irq_safe != pm_runtime_is_irq_safe(dev));
+
+		if (pcdev->irq_safe)
+			clk_disable(pcdev->pclk);
+		else
+			clk_disable_unprepare(pcdev->pclk);
+	}
 
 	return ret;
 }
@@ -107,7 +117,16 @@ static int amba_pm_runtime_resume(struct device *dev)
 	int ret;
 
 	if (dev->driver) {
-		ret = clk_prepare_enable(pcdev->pclk);
+		/*
+		 * Drivers should not change pm_runtime_irq_safe()
+		 * after probe.
+		 */
+		WARN_ON(pcdev->irq_safe != pm_runtime_is_irq_safe(dev));
+
+		if (pcdev->irq_safe)
+			ret = clk_enable(pcdev->pclk);
+		else
+			ret = clk_prepare_enable(pcdev->pclk);
 		/* Failure is probably fatal to the system, but... */
 		if (ret)
 			return ret;
@@ -198,8 +217,10 @@ static int amba_probe(struct device *dev)
 		pm_runtime_enable(dev);
 
 		ret = pcdrv->probe(pcdev, id);
-		if (ret == 0)
+		if (ret == 0) {
+			pcdev->irq_safe = pm_runtime_is_irq_safe(dev);
 			break;
+		}
 
 		pm_runtime_disable(dev);
 		pm_runtime_set_suspended(dev);
diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h
index ac02f9bd63dc..c4bae79851fb 100644
--- a/include/linux/amba/bus.h
+++ b/include/linux/amba/bus.h
@@ -32,6 +32,7 @@ struct amba_device {
 	struct clk		*pclk;
 	unsigned int		periphid;
 	unsigned int		irq[AMBA_NR_IRQS];
+	unsigned int		irq_safe:1;
 };
 
 struct amba_driver {
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists