Re: [RFC][PATCH v3 3/3] input: i8042: Avoid resetting controller on system suspend/resume

[Rafael J. Wysocki]

On Tuesday, October 06, 2015 03:43:08 PM Dmitry Torokhov wrote:
> On Wed, Oct 07, 2015 at 01:08:30AM +0200, Rafael J. Wysocki wrote:
> > On Tuesday, October 06, 2015 03:34:42 PM Dmitry Torokhov wrote:
> > > On Wed, Oct 07, 2015 at 12:53:49AM +0200, Rafael J. Wysocki wrote:
> > > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > > > 
> > > > If the upcoming system suspend is not going to be handled by the
> > > > platform firmware, like in the suspend-to-idle case, it is not
> > > > necessary to reset the controller in i8042_pm_suspend(), so avoid
> > > > doing that.
> > > > 
> > > > Moreover, if the system resume currently in progress has not been
> > > > started by the platform firmware, like in the suspend-to-idle case,
> > > > i8042_controller_resume() need not be called by i8042_pm_resume(),
> > > > so avoid doing that too in that case.
> > > > 
> > > > Additionally, try to catch the event that woke up the system by
> > > > calling the interrupt handler early during system resume if it has
> > > > not been started by the platform firmware.
> > > > 
> > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > > > ---
> > > >  drivers/input/serio/i8042.c |   15 +++++++++++++--
> > > >  1 file changed, 13 insertions(+), 2 deletions(-)
> > > > 
> > > > Index: linux-pm/drivers/input/serio/i8042.c
> > > > ===================================================================
> > > > --- linux-pm.orig/drivers/input/serio/i8042.c
> > > > +++ linux-pm/drivers/input/serio/i8042.c
> > > > @@ -24,6 +24,7 @@
> > > >  #include <linux/platform_device.h>
> > > >  #include <linux/i8042.h>
> > > >  #include <linux/slab.h>
> > > > +#include <linux/suspend.h>
> > > >  
> > > >  #include <asm/io.h>
> > > >  
> > > > @@ -1170,7 +1171,8 @@ static int i8042_pm_suspend(struct devic
> > > >  {
> > > >  	int i;
> > > >  
> > > > -	i8042_controller_reset(true);
> > > > +	if (pm_suspend_via_firmware())
> > > > +		i8042_controller_reset(true);
> > > >  
> > > >  	/* Set up serio interrupts for system wakeup. */
> > > >  	for (i = 0; i < I8042_NUM_PORTS; i++) {
> > > > @@ -1183,6 +1185,14 @@ static int i8042_pm_suspend(struct devic
> > > >  	return 0;
> > > >  }
> > > >  
> > > > +static int i8042_pm_resume_noirq(struct device *dev)
> > > > +{
> > > > +	if (!pm_resume_via_firmware())
> > > > +		i8042_interrupt(0, NULL);
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > >  static int i8042_pm_resume(struct device *dev)
> > > >  {
> > > >  	int i;
> > > > @@ -1199,7 +1209,7 @@ static int i8042_pm_resume(struct device
> > > >  	 * to bring it in a sane state. (In case of S2D we expect
> > > >  	 * BIOS to reset the controller for us.)
> > > >  	 */
> > > > -	return i8042_controller_resume(true);
> > > > +	return pm_resume_via_firmware() ? i8042_controller_resume(true) : 0;
> > > 
> > > What happens if we were going to suspend via firmware so we reset the
> > > controller but then we got wakeup condition and we actually did not
> > > suspend. What pm_resume_via_firmware() will return in this case?
> > 
> > It will return 'false'.  Do we need to resume the controller then?
> 
> Yes.
> 
> >  But I guess
> > 'false' should be passed to i8042_controller_resume() in that case?
> 
> Yes, we do not need to reset the controller in this case, just
> reactivate multiplexing mode, etc.

So something like this I suppose:

---
 drivers/input/serio/i8042.c |   16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

Index: linux-pm/drivers/input/serio/i8042.c
===================================================================
--- linux-pm.orig/drivers/input/serio/i8042.c
+++ linux-pm/drivers/input/serio/i8042.c
@@ -24,6 +24,7 @@
 #include <linux/platform_device.h>
 #include <linux/i8042.h>
 #include <linux/slab.h>
+#include <linux/suspend.h>
 
 #include <asm/io.h>
 
@@ -1170,7 +1171,8 @@ static int i8042_pm_suspend(struct devic
 {
 	int i;
 
-	i8042_controller_reset(true);
+	if (pm_suspend_via_firmware())
+		i8042_controller_reset(true);
 
 	/* Set up serio interrupts for system wakeup. */
 	for (i = 0; i < I8042_NUM_PORTS; i++) {
@@ -1183,6 +1185,14 @@ static int i8042_pm_suspend(struct devic
 	return 0;
 }
 
+static int i8042_pm_resume_noirq(struct device *dev)
+{
+	if (!pm_resume_via_firmware())
+		i8042_interrupt(0, NULL);
+
+	return 0;
+}
+
 static int i8042_pm_resume(struct device *dev)
 {
 	int i;
@@ -1199,7 +1209,8 @@ static int i8042_pm_resume(struct device
 	 * to bring it in a sane state. (In case of S2D we expect
 	 * BIOS to reset the controller for us.)
 	 */
-	return i8042_controller_resume(true);
+	return pm_suspend_via_firmware() ?
+		i8042_controller_resume(pm_resume_via_firmware()) : 0;
 }
 
 static int i8042_pm_thaw(struct device *dev)
@@ -1223,6 +1234,7 @@ static int i8042_pm_restore(struct devic
 
 static const struct dev_pm_ops i8042_pm_ops = {
 	.suspend	= i8042_pm_suspend,
+	.resume_noirq	= i8042_pm_resume_noirq,
 	.resume		= i8042_pm_resume,
 	.thaw		= i8042_pm_thaw,
 	.poweroff	= i8042_pm_reset,

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