From 76edfcf430cc2fa1abcfb910a2643eed102a1590 Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Thu, 27 Jul 2023 10:16:37 -0700 Subject: [PATCH] HID: i2c-hid: Do panel follower work on the system_wq Turning on an i2c-hid device can be a slow process. This is why i2c-hid devices use PROBE_PREFER_ASYNCHRONOUS. Unfortunately, when we're a panel follower the i2c-hid power up sequence now blocks the power on of the panel. Let's fix that by scheduling the work on the system_wq. Reviewed-by: Maxime Ripard Reviewed-by: Benjamin Tissoires Acked-by: Benjamin Tissoires Signed-off-by: Douglas Anderson Link: https://patchwork.freedesktop.org/patch/msgid/20230727101636.v4.10.I962bb462ede779005341c49320740ed95810021d@changeid --- drivers/hid/i2c-hid/i2c-hid-core.c | 50 +++++++++++++++++++++++++++--- 1 file changed, 46 insertions(+), 4 deletions(-) diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c index fc3087a983f5..9601c0605fd9 100644 --- a/drivers/hid/i2c-hid/i2c-hid-core.c +++ b/drivers/hid/i2c-hid/i2c-hid-core.c @@ -110,7 +110,9 @@ struct i2c_hid { struct i2chid_ops *ops; struct drm_panel_follower panel_follower; + struct work_struct panel_follower_prepare_work; bool is_panel_follower; + bool prepare_work_finished; }; static const struct i2c_hid_quirks { @@ -1062,10 +1064,12 @@ err: return ret; } -static int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower) +static void ihid_core_panel_prepare_work(struct work_struct *work) { - struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower); + struct i2c_hid *ihid = container_of(work, struct i2c_hid, + panel_follower_prepare_work); struct hid_device *hid = ihid->hid; + int ret; /* * hid->version is set on the first power up. If it's still zero then @@ -1073,15 +1077,52 @@ static int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower) * steps. */ if (!hid->version) - return __do_i2c_hid_core_initial_power_up(ihid); + ret = __do_i2c_hid_core_initial_power_up(ihid); + else + ret = i2c_hid_core_resume(ihid); - return i2c_hid_core_resume(ihid); + if (ret) + dev_warn(&ihid->client->dev, "Power on failed: %d\n", ret); + else + WRITE_ONCE(ihid->prepare_work_finished, true); + + /* + * The work APIs provide a number of memory ordering guarantees + * including one that says that memory writes before schedule_work() + * are always visible to the work function, but they don't appear to + * guarantee that a write that happened in the work is visible after + * cancel_work_sync(). We'll add a write memory barrier here to match + * with i2c_hid_core_panel_unpreparing() to ensure that our write to + * prepare_work_finished is visible there. + */ + smp_wmb(); +} + +static int i2c_hid_core_panel_prepared(struct drm_panel_follower *follower) +{ + struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower); + + /* + * Powering on a touchscreen can be a slow process. Queue the work to + * the system workqueue so we don't block the panel's power up. + */ + WRITE_ONCE(ihid->prepare_work_finished, false); + schedule_work(&ihid->panel_follower_prepare_work); + + return 0; } static int i2c_hid_core_panel_unpreparing(struct drm_panel_follower *follower) { struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower); + cancel_work_sync(&ihid->panel_follower_prepare_work); + + /* Match with ihid_core_panel_prepare_work() */ + smp_rmb(); + if (!READ_ONCE(ihid->prepare_work_finished)) + return 0; + return i2c_hid_core_suspend(ihid, true); } @@ -1173,6 +1214,7 @@ int i2c_hid_core_probe(struct i2c_client *client, struct i2chid_ops *ops, init_waitqueue_head(&ihid->wait); mutex_init(&ihid->reset_lock); + INIT_WORK(&ihid->panel_follower_prepare_work, ihid_core_panel_prepare_work); /* we need to allocate the command buffer without knowing the maximum * size of the reports. Let's use HID_MIN_BUFFER_SIZE, then we do the -- 2.39.5