[PATCH] i2c: Prevent runtime suspend of adapter when Host Notify is required

[PATCH] i2c: Prevent runtime suspend of adapter when Host Notify is required

[Jarkko Nikula]

Multiple users have reported their Synaptics touchpad has stopped
working between v4.20.1 and v4.20.2 when using SMBus interface.

The culprit for this appeared to be commit c5eb1190074c ("PCI / PM: Allow
runtime PM without callback functions") that fixed the runtime PM for
i2c-i801 SMBus adapter. Those Synaptics touchpad are using i2c-i801
for SMBus communication and testing showed they are able to get back
working by preventing the runtime suspend of adapter.

Normally when i2c-i801 SMBus adapter transmits with the client it resumes
before operation and autosuspends after.

However, if client requires SMBus Host Notify protocol, what those
Synaptics touchpads do, then the host adapter must not go to runtime
suspend since then it cannot process incoming SMBus Host Notify commands
the client may send.

Fix this by keeping I2C/SMBus adapter active in case client requires
Host Notify.

Reported-by: Keijo Vaara <ferdasyn@rocketmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=203297
Fixes: c5eb1190074c ("PCI / PM: Allow runtime PM without callback functions")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
Keijo: could you test this does it fix the issue you reported? This is
practically the same diff I sent earlier what you probably haven't tested yet.
I wanted to send a commitable fix in case it works since I'll be out of
office in a few coming days.
---
 drivers/i2c/i2c-core-base.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 38af18645133..8149c9e32b69 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -327,6 +327,8 @@ static int i2c_device_probe(struct device *dev)
 
 		if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
 			dev_dbg(dev, "Using Host Notify IRQ\n");
+			/* Keep adapter active when Host Notify is required */
+			pm_runtime_get_sync(&client->adapter->dev);
 			irq = i2c_smbus_host_notify_to_irq(client);
 		} else if (dev->of_node) {
 			irq = of_irq_get_byname(dev->of_node, "irq");
@@ -431,6 +433,8 @@ static int i2c_device_remove(struct device *dev)
 	device_init_wakeup(&client->dev, false);
 
 	client->irq = client->init_irq;
+	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
+		pm_runtime_put(&client->adapter->dev);
 
 	return status;
 }
-- 
2.20.1

Re: [PATCH] i2c: Prevent runtime suspend of adapter when Host Notify is required

[Rafael J. Wysocki]

On Tue, Apr 30, 2019 at 4:23 PM Jarkko Nikula
<jarkko.nikula@linux.intel.com> wrote:
>
> Multiple users have reported their Synaptics touchpad has stopped
> working between v4.20.1 and v4.20.2 when using SMBus interface.
>
> The culprit for this appeared to be commit c5eb1190074c ("PCI / PM: Allow
> runtime PM without callback functions") that fixed the runtime PM for
> i2c-i801 SMBus adapter. Those Synaptics touchpad are using i2c-i801
> for SMBus communication and testing showed they are able to get back
> working by preventing the runtime suspend of adapter.
>
> Normally when i2c-i801 SMBus adapter transmits with the client it resumes
> before operation and autosuspends after.
>
> However, if client requires SMBus Host Notify protocol, what those
> Synaptics touchpads do, then the host adapter must not go to runtime
> suspend since then it cannot process incoming SMBus Host Notify commands
> the client may send.
>
> Fix this by keeping I2C/SMBus adapter active in case client requires
> Host Notify.
>
> Reported-by: Keijo Vaara <ferdasyn@rocketmail.com>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=203297
> Fixes: c5eb1190074c ("PCI / PM: Allow runtime PM without callback functions")
> Cc: stable@vger.kernel.org # v4.20+
> Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Or please let me know if you want me to take this.

> ---
> Keijo: could you test this does it fix the issue you reported? This is
> practically the same diff I sent earlier what you probably haven't tested yet.
> I wanted to send a commitable fix in case it works since I'll be out of
> office in a few coming days.
> ---
>  drivers/i2c/i2c-core-base.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 38af18645133..8149c9e32b69 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -327,6 +327,8 @@ static int i2c_device_probe(struct device *dev)
>
>                 if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
>                         dev_dbg(dev, "Using Host Notify IRQ\n");
> +                       /* Keep adapter active when Host Notify is required */
> +                       pm_runtime_get_sync(&client->adapter->dev);
>                         irq = i2c_smbus_host_notify_to_irq(client);
>                 } else if (dev->of_node) {
>                         irq = of_irq_get_byname(dev->of_node, "irq");
> @@ -431,6 +433,8 @@ static int i2c_device_remove(struct device *dev)
>         device_init_wakeup(&client->dev, false);
>
>         client->irq = client->init_irq;
> +       if (client->flags & I2C_CLIENT_HOST_NOTIFY)
> +               pm_runtime_put(&client->adapter->dev);
>
>         return status;
>  }
> --
> 2.20.1
>

Re: [PATCH] i2c: Prevent runtime suspend of adapter when Host Notify is required

[Keijo Vaara]

On Tue, Apr 30, 2019 at 4:23 PM Jarkko Nikula
<jarkko.nikula@linux.intel.com> wrote:
>
> ---
> Keijo: could you test this does it fix the issue you reported? This is
> practically the same diff I sent earlier what you probably haven't tested yet.
> I wanted to send a commitable fix in case it works since I'll be out of
> office in a few coming days.
> ---
>  drivers/i2c/i2c-core-base.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 38af18645133..8149c9e32b69 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -327,6 +327,8 @@ static int i2c_device_probe(struct device *dev)
>
>                if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
>                        dev_dbg(dev, "Using Host Notify IRQ\n");
> +                      /* Keep adapter active when Host Notify is required */
> +                      pm_runtime_get_sync(&client->adapter->dev);
>                        irq = i2c_smbus_host_notify_to_irq(client);
>                } else if (dev->of_node) {
>                        irq = of_irq_get_byname(dev->of_node, "irq");
> @@ -431,6 +433,8 @@ static int i2c_device_remove(struct device *dev)
>        device_init_wakeup(&client->dev, false);
>
>        client->irq = client->init_irq;
> +      if (client->flags & I2C_CLIENT_HOST_NOTIFY)
> +              pm_runtime_put(&client->adapter->dev);
>
>        return status;
>  }
> --
> 2.20.1
>

Thanks guys, I've tested the patch and can confirm it fixes the issue.

Re: [PATCH] i2c: Prevent runtime suspend of adapter when Host Notify is required

[Wolfram Sang]

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On Tue, Apr 30, 2019 at 05:23:22PM +0300, Jarkko Nikula wrote:
> Multiple users have reported their Synaptics touchpad has stopped
> working between v4.20.1 and v4.20.2 when using SMBus interface.
> 
> The culprit for this appeared to be commit c5eb1190074c ("PCI / PM: Allow
> runtime PM without callback functions") that fixed the runtime PM for
> i2c-i801 SMBus adapter. Those Synaptics touchpad are using i2c-i801
> for SMBus communication and testing showed they are able to get back
> working by preventing the runtime suspend of adapter.
> 
> Normally when i2c-i801 SMBus adapter transmits with the client it resumes
> before operation and autosuspends after.
> 
> However, if client requires SMBus Host Notify protocol, what those
> Synaptics touchpads do, then the host adapter must not go to runtime
> suspend since then it cannot process incoming SMBus Host Notify commands
> the client may send.
> 
> Fix this by keeping I2C/SMBus adapter active in case client requires
> Host Notify.
> 
> Reported-by: Keijo Vaara <ferdasyn@rocketmail.com>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=203297
> Fixes: c5eb1190074c ("PCI / PM: Allow runtime PM without callback functions")
> Cc: stable@vger.kernel.org # v4.20+
> Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

Applied to for-current-fixed, thanks!


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