diff mbox series

[4/5] memstick: rtsx_usb_ms: Support runtime power management

Message ID 20180725152515.1833-5-kai.heng.feng@canonical.com (mailing list archive)
State New, archived
Headers show
Series Keep rtsx_usb suspended when there's no card | expand

Commit Message

Kai-Heng Feng July 25, 2018, 3:25 p.m. UTC 
In order to let host's parent device, rtsx_usb, to use USB remote wake
up signaling to do card detection, it needs to be suspended. Hence it's
necessary to add runtime PM support for the memstick host.

To keep memstick host stays suspended when it's not in use, convert the
card detection function from kthread to delayed_work, which can be
scheduled when the host is resumed and can be canceled when the host is
suspended.

Use an idle function check if there's no card and the power mode is
MEMSTICK_POWER_OFF. If both criteria are met, put the device to suspend.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/memstick/host/rtsx_usb_ms.c | 138 ++++++++++++++--------------
 1 file changed, 71 insertions(+), 67 deletions(-)

Comments

'Alan Stern' July 25, 2018, 5:59 p.m. UTC | #1 
On Wed, 25 Jul 2018, Kai-Heng Feng wrote:

> In order to let host's parent device, rtsx_usb, to use USB remote wake
> up signaling to do card detection, it needs to be suspended. Hence it's
> necessary to add runtime PM support for the memstick host.
> 
> To keep memstick host stays suspended when it's not in use, convert the
> card detection function from kthread to delayed_work, which can be
> scheduled when the host is resumed and can be canceled when the host is
> suspended.
> 
> Use an idle function check if there's no card and the power mode is
> MEMSTICK_POWER_OFF. If both criteria are met, put the device to suspend.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

I'm not familiar enough with this driver to comment on specific
instances, but you should carefully go through the code and make sure
that you use pm_runtime_get_noresume() and pm_runtime_put_noidle()
correctly.

The basic idea is to use these when you know beforehand that the device
is already at full power (for _get_noresume) and the usage count will
not go to 0 (for _put_noidle).  If you aren't certain of these
requirements then you should call pm_runtime_get_sync() and
pm_runtime_put().

Alan Stern

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Kai-Heng Feng July 26, 2018, 7:38 a.m. UTC | #2 
> On 2018Jul26, at 01:59, Alan Stern <stern@rowland.harvard.edu> wrote:
> 
> On Wed, 25 Jul 2018, Kai-Heng Feng wrote:
> 
>> In order to let host's parent device, rtsx_usb, to use USB remote wake
>> up signaling to do card detection, it needs to be suspended. Hence it's
>> necessary to add runtime PM support for the memstick host.
>> 
>> To keep memstick host stays suspended when it's not in use, convert the
>> card detection function from kthread to delayed_work, which can be
>> scheduled when the host is resumed and can be canceled when the host is
>> suspended.
>> 
>> Use an idle function check if there's no card and the power mode is
>> MEMSTICK_POWER_OFF. If both criteria are met, put the device to suspend.
>> 
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> 
> I'm not familiar enough with this driver to comment on specific
> instances, but you should carefully go through the code and make sure
> that you use pm_runtime_get_noresume() and pm_runtime_put_noidle()
> correctly.
> 
> The basic idea is to use these when you know beforehand that the device
> is already at full power (for _get_noresume) and the usage count will
> not go to 0 (for _put_noidle).  If you aren't certain of these
> requirements then you should call pm_runtime_get_sync() and
> pm_runtime_put().

There are two different uses for pm_runtime helpers.

The first use case is to prevent parent device, rtsx_usb, from suspending:
pm_runtime_get_noresume()
rtsx_usb_read_register()
pm_runtime_put_noidle()

The second use case, to manage memstick host itself.
memstick_detect_change() powers the host on if there’s a card in slot, and it powers host off when there’s no card.
Once memstick_detect_change() is done, we can check if the host can be suspended.

So we are sure the timing when the power is on or off.

Kai-Heng

> 
> Alan Stern
> 

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diff mbox series

Patch

diff --git a/drivers/memstick/host/rtsx_usb_ms.c b/drivers/memstick/host/rtsx_usb_ms.c
index cd12f3d1c088..126eb310980a 100644
--- a/drivers/memstick/host/rtsx_usb_ms.c
+++ b/drivers/memstick/host/rtsx_usb_ms.c
@@ -40,15 +40,14 @@  struct rtsx_usb_ms {
 
 	struct mutex		host_mutex;
 	struct work_struct	handle_req;
-
-	struct task_struct	*detect_ms;
-	struct completion	detect_ms_exit;
+	struct delayed_work	poll_card;
 
 	u8			ssc_depth;
 	unsigned int		clock;
 	int			power_mode;
 	unsigned char           ifmode;
 	bool			eject;
+	bool			suspend;
 };
 
 static inline struct device *ms_dev(struct rtsx_usb_ms *host)
@@ -524,7 +523,7 @@  static void rtsx_usb_ms_handle_req(struct work_struct *work)
 	int rc;
 
 	if (!host->req) {
-		pm_runtime_get_sync(ms_dev(host));
+		pm_runtime_get_noresume(ms_dev(host));
 		do {
 			rc = memstick_next_req(msh, &host->req);
 			dev_dbg(ms_dev(host), "next req %d\n", rc);
@@ -545,7 +544,7 @@  static void rtsx_usb_ms_handle_req(struct work_struct *work)
 						host->req->error);
 			}
 		} while (!rc);
-		pm_runtime_put(ms_dev(host));
+		pm_runtime_put_noidle(ms_dev(host));
 	}
 
 }
@@ -572,7 +571,7 @@  static int rtsx_usb_ms_set_param(struct memstick_host *msh,
 	dev_dbg(ms_dev(host), "%s: param = %d, value = %d\n",
 			__func__, param, value);
 
-	pm_runtime_get_sync(ms_dev(host));
+	pm_runtime_get_noresume(ms_dev(host));
 	mutex_lock(&ucr->dev_mutex);
 
 	err = rtsx_usb_card_exclusive_check(ucr, RTSX_USB_MS_CARD);
@@ -585,14 +584,14 @@  static int rtsx_usb_ms_set_param(struct memstick_host *msh,
 			break;
 
 		if (value == MEMSTICK_POWER_ON) {
-			pm_runtime_get_sync(ms_dev(host));
+			pm_runtime_get_noresume(ms_dev(host));
 			err = ms_power_on(host);
+			if (err)
+				pm_runtime_put_noidle(ms_dev(host));
 		} else if (value == MEMSTICK_POWER_OFF) {
 			err = ms_power_off(host);
-			if (host->msh->card)
+			if (!err)
 				pm_runtime_put_noidle(ms_dev(host));
-			else
-				pm_runtime_put(ms_dev(host));
 		} else
 			err = -EINVAL;
 		if (!err)
@@ -638,7 +637,7 @@  static int rtsx_usb_ms_set_param(struct memstick_host *msh,
 	}
 out:
 	mutex_unlock(&ucr->dev_mutex);
-	pm_runtime_put(ms_dev(host));
+	pm_runtime_put_noidle(ms_dev(host));
 
 	/* power-on delay */
 	if (param == MEMSTICK_POWER && value == MEMSTICK_POWER_ON)
@@ -648,75 +647,86 @@  static int rtsx_usb_ms_set_param(struct memstick_host *msh,
 	return err;
 }
 
-#ifdef CONFIG_PM_SLEEP
-static int rtsx_usb_ms_suspend(struct device *dev)
+#ifdef CONFIG_PM
+static int rtsx_usb_ms_runtime_suspend(struct device *dev)
 {
 	struct rtsx_usb_ms *host = dev_get_drvdata(dev);
 	struct memstick_host *msh = host->msh;
 
-	dev_dbg(ms_dev(host), "--> %s\n", __func__);
-
+	host->suspend = true;
 	memstick_suspend_host(msh);
+
 	return 0;
 }
 
-static int rtsx_usb_ms_resume(struct device *dev)
+static int rtsx_usb_ms_runtime_resume(struct device *dev)
 {
 	struct rtsx_usb_ms *host = dev_get_drvdata(dev);
 	struct memstick_host *msh = host->msh;
 
-	dev_dbg(ms_dev(host), "--> %s\n", __func__);
-
 	memstick_resume_host(msh);
+	host->suspend = false;
+	schedule_delayed_work(&host->poll_card, 100);
+
 	return 0;
 }
-#endif /* CONFIG_PM_SLEEP */
 
-/*
- * Thread function of ms card slot detection. The thread starts right after
- * successful host addition. It stops while the driver removal function sets
- * host->eject true.
- */
-static int rtsx_usb_detect_ms_card(void *__host)
+static int rtsx_usb_ms_runtime_idle(struct device *dev)
+{
+	struct rtsx_usb_ms *host = dev_get_drvdata(dev);
+
+	if (!host->msh->card && host->power_mode == MEMSTICK_POWER_OFF) {
+		pm_schedule_suspend(dev, 0);
+		return 0;
+	}
+
+	return -EAGAIN;
+}
+
+static UNIVERSAL_DEV_PM_OPS(rtsx_usb_ms_pm_ops,
+		rtsx_usb_ms_runtime_suspend, rtsx_usb_ms_runtime_resume,
+		rtsx_usb_ms_runtime_idle);
+#endif /* CONFIG_PM */
+
+static void rtsx_usb_ms_poll_card(struct work_struct *work)
 {
-	struct rtsx_usb_ms *host = (struct rtsx_usb_ms *)__host;
+	struct rtsx_usb_ms *host = container_of(work, struct rtsx_usb_ms,
+			poll_card.work);
 	struct rtsx_ucr *ucr = host->ucr;
-	u8 val = 0;
 	int err;
+	u8 val;
 
-	for (;;) {
-		pm_runtime_get_sync(ms_dev(host));
-		mutex_lock(&ucr->dev_mutex);
+	if (host->eject || host->suspend)
+		return;
 
-		/* Check pending MS card changes */
-		err = rtsx_usb_read_register(ucr, CARD_INT_PEND, &val);
-		if (err) {
-			mutex_unlock(&ucr->dev_mutex);
-			goto poll_again;
-		}
-
-		/* Clear the pending */
-		rtsx_usb_write_register(ucr, CARD_INT_PEND,
-				XD_INT | MS_INT | SD_INT,
-				XD_INT | MS_INT | SD_INT);
+	pm_runtime_get_noresume(ms_dev(host));
+	mutex_lock(&ucr->dev_mutex);
 
+	/* Check pending MS card changes */
+	err = rtsx_usb_read_register(ucr, CARD_INT_PEND, &val);
+	if (err) {
 		mutex_unlock(&ucr->dev_mutex);
+		goto poll_again;
+	}
 
-		if (val & MS_INT) {
-			dev_dbg(ms_dev(host), "MS slot change detected\n");
-			memstick_detect_change(host->msh);
-		}
+	/* Clear the pending */
+	rtsx_usb_write_register(ucr, CARD_INT_PEND,
+			XD_INT | MS_INT | SD_INT,
+			XD_INT | MS_INT | SD_INT);
 
-poll_again:
-		pm_runtime_put(ms_dev(host));
-		if (host->eject)
-			break;
+	mutex_unlock(&ucr->dev_mutex);
+	pm_runtime_put_noidle(ms_dev(host));
 
-		schedule_timeout_idle(HZ);
+	if (val & MS_INT) {
+		dev_dbg(ms_dev(host), "MS slot change detected\n");
+		memstick_detect_change(host->msh);
 	}
 
-	complete(&host->detect_ms_exit);
-	return 0;
+	pm_runtime_idle(ms_dev(host));
+
+poll_again:
+	if (!host->eject && !host->suspend)
+		schedule_delayed_work(&host->poll_card, 100);
 }
 
 static int rtsx_usb_ms_drv_probe(struct platform_device *pdev)
@@ -747,26 +757,21 @@  static int rtsx_usb_ms_drv_probe(struct platform_device *pdev)
 	mutex_init(&host->host_mutex);
 	INIT_WORK(&host->handle_req, rtsx_usb_ms_handle_req);
 
-	init_completion(&host->detect_ms_exit);
-	host->detect_ms = kthread_create(rtsx_usb_detect_ms_card, host,
-			"rtsx_usb_ms_%d", pdev->id);
-	if (IS_ERR(host->detect_ms)) {
-		dev_dbg(&(pdev->dev),
-				"Unable to create polling thread.\n");
-		err = PTR_ERR(host->detect_ms);
-		goto err_out;
-	}
+	INIT_DELAYED_WORK(&host->poll_card, rtsx_usb_ms_poll_card);
 
 	msh->request = rtsx_usb_ms_request;
 	msh->set_param = rtsx_usb_ms_set_param;
 	msh->caps = MEMSTICK_CAP_PAR4;
 
-	pm_runtime_enable(&pdev->dev);
+	pm_runtime_set_active(ms_dev(host));
+	pm_runtime_enable(ms_dev(host));
+
 	err = memstick_add_host(msh);
 	if (err)
 		goto err_out;
 
-	wake_up_process(host->detect_ms);
+	schedule_delayed_work(&host->poll_card, 100);
+
 	return 0;
 err_out:
 	memstick_free_host(msh);
@@ -782,6 +787,7 @@  static int rtsx_usb_ms_drv_remove(struct platform_device *pdev)
 	msh = host->msh;
 	host->eject = true;
 	cancel_work_sync(&host->handle_req);
+	cancel_delayed_work_sync(&host->poll_card);
 
 	mutex_lock(&host->host_mutex);
 	if (host->req) {
@@ -797,7 +803,6 @@  static int rtsx_usb_ms_drv_remove(struct platform_device *pdev)
 	}
 	mutex_unlock(&host->host_mutex);
 
-	wait_for_completion(&host->detect_ms_exit);
 	memstick_remove_host(msh);
 	memstick_free_host(msh);
 
@@ -816,9 +821,6 @@  static int rtsx_usb_ms_drv_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static SIMPLE_DEV_PM_OPS(rtsx_usb_ms_pm_ops,
-		rtsx_usb_ms_suspend, rtsx_usb_ms_resume);
-
 static struct platform_device_id rtsx_usb_ms_ids[] = {
 	{
 		.name = "rtsx_usb_ms",
@@ -834,7 +836,9 @@  static struct platform_driver rtsx_usb_ms_driver = {
 	.id_table       = rtsx_usb_ms_ids,
 	.driver		= {
 		.name	= "rtsx_usb_ms",
+#ifdef CONFIG_PM
 		.pm	= &rtsx_usb_ms_pm_ops,
+#endif
 	},
 };
 module_platform_driver(rtsx_usb_ms_driver);