releases/5.0.14/i2c-prevent-runtime-suspend-of-adapter-when-host-notify-is-required.patch

   1 From 72bfcee11cf89509795c56b0e40a3785ab00bbdd Mon Sep 17 00:00:00 2001
   2 From: Jarkko Nikula <jarkko.nikula@linux.intel.com>
   3 Date: Tue, 30 Apr 2019 17:23:22 +0300
   4 Subject: i2c: Prevent runtime suspend of adapter when Host Notify is required
   5
   6 From: Jarkko Nikula <jarkko.nikula@linux.intel.com>
   7
   8 commit 72bfcee11cf89509795c56b0e40a3785ab00bbdd upstream.
   9
  10 Multiple users have reported their Synaptics touchpad has stopped
  11 working between v4.20.1 and v4.20.2 when using SMBus interface.
  12
  13 The culprit for this appeared to be commit c5eb1190074c ("PCI / PM: Allow
  14 runtime PM without callback functions") that fixed the runtime PM for
  15 i2c-i801 SMBus adapter. Those Synaptics touchpad are using i2c-i801
  16 for SMBus communication and testing showed they are able to get back
  17 working by preventing the runtime suspend of adapter.
  18
  19 Normally when i2c-i801 SMBus adapter transmits with the client it resumes
  20 before operation and autosuspends after.
  21
  22 However, if client requires SMBus Host Notify protocol, what those
  23 Synaptics touchpads do, then the host adapter must not go to runtime
  24 suspend since then it cannot process incoming SMBus Host Notify commands
  25 the client may send.
  26
  27 Fix this by keeping I2C/SMBus adapter active in case client requires
  28 Host Notify.
  29
  30 Reported-by: Keijo Vaara <ferdasyn@rocketmail.com>
  31 Link: https://bugzilla.kernel.org/show_bug.cgi?id=203297
  32 Fixes: c5eb1190074c ("PCI / PM: Allow runtime PM without callback functions")
  33 Cc: stable@vger.kernel.org # v4.20+
  34 Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
  35 Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  36 Tested-by: Keijo Vaara <ferdasyn@rocketmail.com>
  37 Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
  38 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  39
  40 ---
  41  drivers/i2c/i2c-core-base.c |    4 ++++
  42  1 file changed, 4 insertions(+)
  43
  44 --- a/drivers/i2c/i2c-core-base.c
  45 +++ b/drivers/i2c/i2c-core-base.c
  46 @@ -327,6 +327,8 @@ static int i2c_device_probe(struct devic
  47
  48                 if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
  49                         dev_dbg(dev, "Using Host Notify IRQ\n");
  50 +                       /* Keep adapter active when Host Notify is required */
  51 +                       pm_runtime_get_sync(&client->adapter->dev);
  52                         irq = i2c_smbus_host_notify_to_irq(client);
  53                 } else if (dev->of_node) {
  54                         irq = of_irq_get_byname(dev->of_node, "irq");
  55 @@ -431,6 +433,8 @@ static int i2c_device_remove(struct devi
  56         device_init_wakeup(&client->dev, false);
  57
  58         client->irq = client->init_irq;
  59 +       if (client->flags & I2C_CLIENT_HOST_NOTIFY)
  60 +               pm_runtime_put(&client->adapter->dev);
  61
  62         return status;
  63  }