[PATCH v3] HID: i2c-hid: Fix suspend/resume when already runtime suspended

[PATCH v3] HID: i2c-hid: Fix suspend/resume when already runtime suspended

[Dmitry Torokhov]

On ACPI-based systems ACPI power domain code runtime resumes device before
calling suspend method, which ensures that i2c-hid suspend code starts with
device not in low-power state and with interrupts enabled.

On other systems, especially if device is not a part of any power domain,
we may end up calling driver's system-level suspend routine while the
device is runtime-suspended (with controller in presumably low power state
and interrupts disabled). This will result in interrupts being essentially
disabled twice, and we will only re-enable them after both system resume
and runtime resume methods complete. Unfortunately i2c_hid_resume() calls
i2c_hid_hwreset() and that only works properly if interrupts are enabled.

Also if device is runtime-suspended driver's suspend code may fail if it
tries to issue I/O requests.

Let's fix it by runtime-resuming the device if we need to run HID driver's
suspend code and also disabling interrupts only if device is not already
runtime-suspended. Also on resume we mark the device as running at full
power (since that is what resetting will do to it).

Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
---

This is an uprev of a patch that Doug sent a year ago (see
https://patchwork.kernel.org/patch/5970731/), adjusted to the latest
mainline. The change from v2 is that we runtime-resume the device before
calling into HID driver's suspend callback.


 drivers/hid/i2c-hid/i2c-hid.c | 43 +++++++++++++++++++++++++++++++------------
 1 file changed, 31 insertions(+), 12 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index b921693..1f62751 100644
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -1108,13 +1108,30 @@ static int i2c_hid_suspend(struct device *dev)
 	struct i2c_client *client = to_i2c_client(dev);
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
 	struct hid_device *hid = ihid->hid;
-	int ret = 0;
+	int ret;
 	int wake_status;
 
-	if (hid->driver && hid->driver->suspend)
+	if (hid->driver && hid->driver->suspend) {
+		/*
+		 * Wake up the device so that IO issues in
+		 * HID driver's suspend code can succeed.
+		 */
+		ret = pm_runtime_resume(dev);
+		if (ret < 0)
+			return ret;
+
 		ret = hid->driver->suspend(hid, PMSG_SUSPEND);
+		if (ret < 0)
+			return ret;
+	}
+
+	if (!pm_runtime_suspended(dev)) {
+		/* Save some power */
+		i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
+
+		disable_irq(ihid->irq);
+	}
 
-	disable_irq(ihid->irq);
 	if (device_may_wakeup(&client->dev)) {
 		wake_status = enable_irq_wake(ihid->irq);
 		if (!wake_status)
@@ -1124,10 +1141,7 @@ static int i2c_hid_suspend(struct device *dev)
 				wake_status);
 	}
 
-	/* Save some power */
-	i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
-
-	return ret;
+	return 0;
 }
 
 static int i2c_hid_resume(struct device *dev)
@@ -1138,11 +1152,6 @@ static int i2c_hid_resume(struct device *dev)
 	struct hid_device *hid = ihid->hid;
 	int wake_status;
 
-	enable_irq(ihid->irq);
-	ret = i2c_hid_hwreset(client);
-	if (ret)
-		return ret;
-
 	if (device_may_wakeup(&client->dev) && ihid->irq_wake_enabled) {
 		wake_status = disable_irq_wake(ihid->irq);
 		if (!wake_status)
@@ -1152,6 +1161,16 @@ static int i2c_hid_resume(struct device *dev)
 				wake_status);
 	}
 
+	/* We'll resume to full power */
+	pm_runtime_disable(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
+	enable_irq(ihid->irq);
+	ret = i2c_hid_hwreset(client);
+	if (ret)
+		return ret;
+
 	if (hid->driver && hid->driver->reset_resume) {
 		ret = hid->driver->reset_resume(hid);
 		return ret;
-- 
2.7.0.rc3.207.g0ac5344


-- 
Dmitry

Re: [PATCH v3] HID: i2c-hid: Fix suspend/resume when already runtime suspended

[Benson Leung]

On Tue, Mar 8, 2016 at 3:03 PM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> On ACPI-based systems ACPI power domain code runtime resumes device before
> calling suspend method, which ensures that i2c-hid suspend code starts with
> device not in low-power state and with interrupts enabled.
>
> On other systems, especially if device is not a part of any power domain,
> we may end up calling driver's system-level suspend routine while the
> device is runtime-suspended (with controller in presumably low power state
> and interrupts disabled). This will result in interrupts being essentially
> disabled twice, and we will only re-enable them after both system resume
> and runtime resume methods complete. Unfortunately i2c_hid_resume() calls
> i2c_hid_hwreset() and that only works properly if interrupts are enabled.
>
> Also if device is runtime-suspended driver's suspend code may fail if it
> tries to issue I/O requests.
>
> Let's fix it by runtime-resuming the device if we need to run HID driver's
> suspend code and also disabling interrupts only if device is not already
> runtime-suspended. Also on resume we mark the device as running at full
> power (since that is what resetting will do to it).
>
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Dmitry Torokhov <dtor@chromium.org>

Reviewed-by: Benson Leung <bleung@chromium.org>

> ---
>
> This is an uprev of a patch that Doug sent a year ago (see
> https://patchwork.kernel.org/patch/5970731/), adjusted to the latest
> mainline. The change from v2 is that we runtime-resume the device before
> calling into HID driver's suspend callback.




-- 
Benson Leung
Senior Software Engineer, Chrom* OS
bleung@chromium.org

Re: [PATCH v3] HID: i2c-hid: Fix suspend/resume when already runtime suspended

[Mika Westerberg]

On Tue, Mar 08, 2016 at 03:03:23PM -0800, Dmitry Torokhov wrote:
> On ACPI-based systems ACPI power domain code runtime resumes device before
> calling suspend method, which ensures that i2c-hid suspend code starts with
> device not in low-power state and with interrupts enabled.
> 
> On other systems, especially if device is not a part of any power domain,
> we may end up calling driver's system-level suspend routine while the
> device is runtime-suspended (with controller in presumably low power state
> and interrupts disabled). This will result in interrupts being essentially
> disabled twice, and we will only re-enable them after both system resume
> and runtime resume methods complete. Unfortunately i2c_hid_resume() calls
> i2c_hid_hwreset() and that only works properly if interrupts are enabled.
> 
> Also if device is runtime-suspended driver's suspend code may fail if it
> tries to issue I/O requests.
> 
> Let's fix it by runtime-resuming the device if we need to run HID driver's
> suspend code and also disabling interrupts only if device is not already
> runtime-suspended. Also on resume we mark the device as running at full
> power (since that is what resetting will do to it).
> 
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Dmitry Torokhov <dtor@chromium.org>

Tested on a couple of Intel Skylake and Baytrail based systems and power
management of I2C connected HID devices still seems to work just fine.

Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Re: [PATCH v3] HID: i2c-hid: Fix suspend/resume when already runtime suspended

[Benjamin Tissoires]

On Mar 09 2016 or thereabouts, Mika Westerberg wrote:
> On Tue, Mar 08, 2016 at 03:03:23PM -0800, Dmitry Torokhov wrote:
> > On ACPI-based systems ACPI power domain code runtime resumes device before
> > calling suspend method, which ensures that i2c-hid suspend code starts with
> > device not in low-power state and with interrupts enabled.
> > 
> > On other systems, especially if device is not a part of any power domain,
> > we may end up calling driver's system-level suspend routine while the
> > device is runtime-suspended (with controller in presumably low power state
> > and interrupts disabled). This will result in interrupts being essentially
> > disabled twice, and we will only re-enable them after both system resume
> > and runtime resume methods complete. Unfortunately i2c_hid_resume() calls
> > i2c_hid_hwreset() and that only works properly if interrupts are enabled.
> > 
> > Also if device is runtime-suspended driver's suspend code may fail if it
> > tries to issue I/O requests.
> > 
> > Let's fix it by runtime-resuming the device if we need to run HID driver's
> > suspend code and also disabling interrupts only if device is not already
> > runtime-suspended. Also on resume we mark the device as running at full
> > power (since that is what resetting will do to it).
> > 
> > Signed-off-by: Doug Anderson <dianders@chromium.org>
> > Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
> 
> Tested on a couple of Intel Skylake and Baytrail based systems and power
> management of I2C connected HID devices still seems to work just fine.
> 
> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Well, I have completely no way of testing this myself, and I blindly
trust Mika, Dmitry and the others for doing the right thing :).

Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Cheers,
Benjamin

Re: [PATCH v3] HID: i2c-hid: Fix suspend/resume when already runtime suspended

[Jiri Kosina]

On Tue, 8 Mar 2016, Dmitry Torokhov wrote:

> On ACPI-based systems ACPI power domain code runtime resumes device before
> calling suspend method, which ensures that i2c-hid suspend code starts with
> device not in low-power state and with interrupts enabled.
> 
> On other systems, especially if device is not a part of any power domain,
> we may end up calling driver's system-level suspend routine while the
> device is runtime-suspended (with controller in presumably low power state
> and interrupts disabled). This will result in interrupts being essentially
> disabled twice, and we will only re-enable them after both system resume
> and runtime resume methods complete. Unfortunately i2c_hid_resume() calls
> i2c_hid_hwreset() and that only works properly if interrupts are enabled.
> 
> Also if device is runtime-suspended driver's suspend code may fail if it
> tries to issue I/O requests.
> 
> Let's fix it by runtime-resuming the device if we need to run HID driver's
> suspend code and also disabling interrupts only if device is not already
> runtime-suspended. Also on resume we mark the device as running at full
> power (since that is what resetting will do to it).
> 
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Dmitry Torokhov <dtor@chromium.org>

Applied to for-4.6/i2c-hid, thanks.

On Wed, 9 Mar 2016, Benjamin Tissoires wrote:

> Well, I have completely no way of testing this myself, and I blindly
> trust Mika, Dmitry and the others for doing the right thing :).

Welcome to the wonderful world of linux kernel maintainers! :p

Thanks,

-- 
Jiri Kosina
SUSE Labs