Input: psmouse - set up dependency between PS/2 and SMBus companions

When we switch from emulated PS/2 to native (RMI4 or Elan) protocols, we
create SMBus companion devices that are attached to I2C/SMBus controllers.
However, when suspending and resuming, we also need to make sure that we
take into account the PS/2 device they are associated with, so that PS/2
device is suspended after the companion and resumed before it, otherwise
companions will not work properly. Before I2C devices were marked for
asynchronous suspend/resume, this ordering happened naturally, but now we
need to enforce it by establishing device links, with PS/2 devices being
suppliers and SMBus companions being consumers.

Fixes: 172d931910e1 ("i2c: enable async suspend/resume on i2c client devices")
Reported-and-tested-by: Hugh Dickins <hughd@google.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Link: https://lore.kernel.org/r/89456fcd-a113-4c82-4b10-a9bcaefac68f@google.com
Link: https://lore.kernel.org/r/YgwQN8ynO88CPMju@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/mouse/psmouse-smbus.c b/drivers/input/mouse/psmouse-smbus.c
index a472489..164f6c7 100644 (file)
--- a/drivers/input/mouse/psmouse-smbus.c
+++ b/drivers/input/mouse/psmouse-smbus.c
@@ -75,6 +75,8 @@ static void psmouse_smbus_detach_i2c_client(struct i2c_client *client)
                                    "Marking SMBus companion %s as gone\n",
                                    dev_name(&smbdev->client->dev));
                        smbdev->dead = true;
+                       device_link_remove(&smbdev->client->dev,
+                                          &smbdev->psmouse->ps2dev.serio->dev);
                        serio_rescan(smbdev->psmouse->ps2dev.serio);
                } else {
                        list_del(&smbdev->node);
@@ -174,6 +176,8 @@ static void psmouse_smbus_disconnect(struct psmouse *psmouse)
                kfree(smbdev);
        } else {
                smbdev->dead = true;
+               device_link_remove(&smbdev->client->dev,
+                                  &psmouse->ps2dev.serio->dev);
                psmouse_dbg(smbdev->psmouse,
                            "posting removal request for SMBus companion %s\n",
                            dev_name(&smbdev->client->dev));
@@ -270,6 +274,12 @@ int psmouse_smbus_init(struct psmouse *psmouse,
 
        if (smbdev->client) {
                /* We have our companion device */
+               if (!device_link_add(&smbdev->client->dev,
+                                    &psmouse->ps2dev.serio->dev,
+                                    DL_FLAG_STATELESS))
+                       psmouse_warn(psmouse,
+                                    "failed to set up link with iSMBus companion %s\n",
+                                    dev_name(&smbdev->client->dev));
                return 0;
        }