Re: [PATCH 1/9] mmc: sdhci-pci: Stop calling sdhci_enable_irq_wakeups()

On 21/12/17 17:33, Ulf Hansson wrote:

+ linux-pm, Rafael, Geert

On 21 December 2017 at 15:25, Adrian Hunter [off-list ref] wrote:

quoted

On 21/12/17 16:15, Ulf Hansson wrote:

quoted

On 20 December 2017 at 09:18, Adrian Hunter [off-list ref] wrote:

quoted

sdhci_enable_irq_wakeups() is already called by sdhci_suspend_host() so
sdhci-pci should not need to call it. However sdhci_suspend_host() only
calls it if wakeups are enabled, and sdhci-pci does not enable them until
after calling sdhci_suspend_host(). So move the calls to
sdhci_pci_init_wakeup() before calling sdhci_suspend_host(), and
stop calling sdhci_enable_irq_wakeups(). That results in some
simplification because sdhci_pci_suspend_host() and
__sdhci_pci_suspend_host() no longer need to be separate functions.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/mmc/host/sdhci-pci-core.c | 58 ++++++++++++++-------------------------
 1 file changed, 21 insertions(+), 37 deletions(-)

diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
index 110c634cfb43..2ffc09f088ee 100644
--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c

@@ -39,10 +39,29 @@
 static void sdhci_pci_hw_reset(struct sdhci_host *host);

 #ifdef CONFIG_PM_SLEEP
-static int __sdhci_pci_suspend_host(struct sdhci_pci_chip *chip)
+static int sdhci_pci_init_wakeup(struct sdhci_pci_chip *chip)
+{
+       mmc_pm_flag_t pm_flags = 0;
+       int i;
+
+       for (i = 0; i < chip->num_slots; i++) {
+               struct sdhci_pci_slot *slot = chip->slots[i];
+
+               if (slot)
+                       pm_flags |= slot->host->mmc->pm_flags;
+       }
+
+       return device_init_wakeup(&chip->pdev->dev,
+                                 (pm_flags & MMC_PM_KEEP_POWER) &&
+                                 (pm_flags & MMC_PM_WAKE_SDIO_IRQ));

A couple of comments here.

Wakeup settings shouldn't be changed during system suspend. That means
we shouldn't call device_init_wakeup() (or device_set_wakeup_enable()
for that matter) here.

Instead, device_init_wakeup() should be called during ->probe(), while
device_set_wakeup_enable() should normally *not* have to be called at
all by drivers. There are a exceptions for device_set_wakeup_enable(),
however it should not have to be called during system suspend, at
least.

Of course, I realize that you are not changing the behavior in this
regards in this patch, so I am fine this anyway.

My point is, that the end result while doing this improvements in this
series, should strive to that device_init_wakeup() and
device_set_wakeup_enable() becomes used correctly. I don't think that
is the case, or is it?

Unfortunately we don't find out what the SDIO driver wants to do (i.e
pm_flags & MMC_PM_WAKE_SDIO_IRQ) until suspend.

That's true! Of course, we need to be able to act on this, somehow.

quoted

I considered enabling wakeups by default but wasn't sure that would not
increase power consumption in devices not expecting it.

I understand the problem, believe me. However, I would rather like to
try to find a generic solution to these problems, else we will keep
abusing existing wakeups APIs.

For your information, I have been working on several issues on how to
handle the "wakeup path" correctly, which is linked to this problem.
See a few quite small series for this below [1], [2].

I think the general problems can be described liked this:

1) The dev->power.wakeup_path flag doesn't get set for the device by
the PM core, in case device_set_wakeup_enable() is called from a
->suspend() callback. That also means, that the parent device don't
get its >power.wakeup_path flag set in __device_suspend() by the PM
core, while this may be expected by upper layers (PM domains, middle
layers).

2) device_may_wakeup() doesn't tell us the hole story about the
wakeup. Only that is *may* be configured. :-)
So in cases when device_may_wakeup() returns true, we still have these
three conditions to consider, which we currently can't distinguish
between:

*) The wakeup is configured and enabled, so the device should be
enabled in the wakeup path.

**) The wakeup is configured and enabled, but as an out-band-wakeup
signal (like a GPIO IRQ). This means the device shouldn't be enabled
in the wakeup path.

So what about just adding can_oob_wakeup and oob_wakeup i.e.

diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 0f651efc58a1..162a511286b7 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c

@@ -323,23 +323,32 @@ static ssize_t pm_qos_no_power_off_store(struct device *dev,
 static ssize_t wakeup_show(struct device *dev, struct device_attribute *attr,
 			   char *buf)
 {
-	return sprintf(buf, "%s\n", device_can_wakeup(dev)
-		? (device_may_wakeup(dev) ? _enabled : _disabled)
-		: "");
+	return sprintf(buf, "%s\n", device_may_wakeup(dev) ||
+				    device_may_oob_wakeup(dev) ? _enabled :
+				    device_can_wakeup(dev) ||
+				    device_can_oob_wakeup(dev) ? _disabled :
+				    "");
 }
 
 static ssize_t wakeup_store(struct device *dev, struct device_attribute *attr,
 			    const char *buf, size_t n)
 {
-	if (!device_can_wakeup(dev))
+	bool enable = false;
+
+	if (!device_can_wakeup(dev) && !device_can_oob_wakeup(dev))
 		return -EINVAL;
 
 	if (sysfs_streq(buf, _enabled))
-		device_set_wakeup_enable(dev, 1);
-	else if (sysfs_streq(buf, _disabled))
-		device_set_wakeup_enable(dev, 0);
-	else
+		enable = true;
+	else if (!sysfs_streq(buf, _disabled))
 		return -EINVAL;
+
+	if (device_can_wakeup(dev))
+		device_set_wakeup_enable(dev, enable);
+
+	if (device_can_oob_wakeup(dev))
+		device_set_oob_wakeup_enable(dev, enable);
+
 	return n;
 }
 

diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index e73a081c6397..13e176edc3d7 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c

@@ -392,6 +392,20 @@ int device_wakeup_disable(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(device_wakeup_disable);
 
+static void wakeup_sysfs_add_remove(struct device *dev, bool capable)
+{
+	if (device_is_registered(dev) && !list_empty(&dev->power.entry)) {
+		if (capable) {
+			int ret = wakeup_sysfs_add(dev);
+
+			if (ret)
+				dev_info(dev, "Wakeup sysfs attributes not added\n");
+		} else {
+			wakeup_sysfs_remove(dev);
+		}
+	}
+}
+
 /**
  * device_set_wakeup_capable - Set/reset device wakeup capability flag.
  * @dev: Device to handle.

@@ -410,20 +424,35 @@ void device_set_wakeup_capable(struct device *dev, bool capable)
 		return;
 
 	dev->power.can_wakeup = capable;
-	if (device_is_registered(dev) && !list_empty(&dev->power.entry)) {
-		if (capable) {
-			int ret = wakeup_sysfs_add(dev);
-
-			if (ret)
-				dev_info(dev, "Wakeup sysfs attributes not added\n");
-		} else {
-			wakeup_sysfs_remove(dev);
-		}
-	}
+	wakeup_sysfs_add_remove(dev, capable);
 }
 EXPORT_SYMBOL_GPL(device_set_wakeup_capable);
 
 /**
+ * device_set_oob_wakeup_capable - Set/reset device oob wakeup capability flag.
+ * @dev: Device to handle.
+ * @capable: Whether or not @dev is capable of out-of-band wake up of the system
+ * from sleep.
+ *
+ * If @capable is set, set the @dev's power.can_oob_wakeup flag and add its
+ * wakeup-related attributes to sysfs.  Otherwise, unset the @dev's
+ * power.can_oob_wakeup flag and remove its wakeup-related attributes from
+ * sysfs.
+ *
+ * This function may sleep and it can't be called from any context where
+ * sleeping is not allowed.
+ */
+void device_set_oob_wakeup_capable(struct device *dev, bool capable)
+{
+	if (!!dev->power.can_oob_wakeup == !!capable)
+		return;
+
+	dev->power.can_oob_wakeup = capable;
+	wakeup_sysfs_add_remove(dev, capable);
+}
+EXPORT_SYMBOL_GPL(device_set_oob_wakeup_capable);
+
+/**
  * device_init_wakeup - Device wakeup initialization.
  * @dev: Device to handle.
  * @enable: Whether or not to enable @dev as a wakeup device.

diff --git a/include/linux/pm.h b/include/linux/pm.h
index e723b78d8357..22cfcacc0095 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h

@@ -585,6 +585,8 @@ struct pm_subsys_data {
 struct dev_pm_info {
 	pm_message_t		power_state;
 	unsigned int		can_wakeup:1;
+	unsigned int		can_oob_wakeup:1;
+	unsigned int		oob_wakeup:1;
 	unsigned int		async_suspend:1;
 	bool			in_dpm_list:1;	/* Owned by the PM core */
 	bool			is_prepared:1;	/* Owned by the PM core */

diff --git a/include/linux/pm_wakeup.h b/include/linux/pm_wakeup.h
index 4238dde0aaf0..64252cb0f97a 100644
--- a/include/linux/pm_wakeup.h
+++ b/include/linux/pm_wakeup.h

@@ -83,11 +83,30 @@ static inline bool device_can_wakeup(struct device *dev)
 	return dev->power.can_wakeup;
 }
 
+static inline bool device_can_oob_wakeup(struct device *dev)
+{
+	return dev->power.can_oob_wakeup;
+}
+
 static inline bool device_may_wakeup(struct device *dev)
 {
 	return dev->power.can_wakeup && !!dev->power.wakeup;
 }
 
+static inline bool device_may_oob_wakeup(struct device *dev)
+{
+	return dev->power.can_oob_wakeup && dev->power.oob_wakeup;
+}
+
+static inline int device_set_oob_wakeup_enable(struct device *dev, bool enable)
+{
+	if (!dev->power.can_oob_wakeup)
+		return -EINVAL;
+
+	dev->power.oob_wakeup = enable;
+	return 0;
+}
+
 static inline void device_set_wakeup_path(struct device *dev)
 {
 	dev->power.wakeup_path = true;

***) The wakeup isn't configured, thus disabled, because there are no
consumers of the wakeup IRQ registered (as may be the case for SDIO
IRQ). This also means the device shouldn't be enabled in the wakeup
path.

Potentially, one could consider **) and ***) being treated in the same
way, via using an opt-out method, avoiding the wakeup path to be
enabled. Currently I have been thinking of adding an "OUT_BAND_WAKEUP"
driver PM flag, to deal with this, however there may be other
preferred options.

Kind regards
Uffe

[1]
https://www.spinics.net/lists/linux-renesas-soc/msg21421.html
[2]
https://www.spinics.net/lists/linux-renesas-soc/msg20122.html
(Actually the discussions there concluded that we may need an
"OUT_BAND_WAKEUP" flag instead)