From: Douglas Anderson <dianders@chromium.org>
To: Jiri Kosina <jikos@kernel.org>,
Benjamin Tissoires <benjamin.tissoires@redhat.com>,
Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Conor Dooley <conor+dt@kernel.org>,
Neil Armstrong <neil.armstrong@linaro.org>,
Sam Ravnborg <sam@ravnborg.org>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>
Cc: dri-devel@lists.freedesktop.org,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
linux-input@vger.kernel.org, Daniel Vetter <daniel@ffwll.ch>,
linux-kernel@vger.kernel.org, hsinyi@google.com,
cros-qcom-dts-watchers@chromium.org, devicetree@vger.kernel.org,
yangcong5@huaqin.corp-partner.google.com,
linux-arm-msm@vger.kernel.org,
Chris Morgan <macroalpha82@gmail.com>,
Douglas Anderson <dianders@chromium.org>
Subject: [PATCH v2 09/10] HID: i2c-hid: Do panel follower work on the system_wq
Date: Wed, 7 Jun 2023 14:49:31 -0700 [thread overview]
Message-ID: <20230607144931.v2.9.I962bb462ede779005341c49320740ed95810021d@changeid> (raw)
In-Reply-To: <20230607215224.2067679-1-dianders@chromium.org>
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.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
Changes in v2:
- ihid_core_panel_prepare_work() is now static.
- Improve documentation for smp_wmb().
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 368db3ae612f..de1a0624be08 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 @@ static int i2c_hid_core_initial_power_up(struct i2c_hid *ihid)
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 i2c_hid_core_initial_power_up(ihid);
+ ret = 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);
}
@@ -1124,6 +1165,7 @@ 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
--
2.41.0.162.gfafddb0af9-goog
next prev parent reply other threads:[~2023-06-07 21:54 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-07 21:49 [PATCH v2 00/10] drm/panel and i2c-hid: Allow panels and touchscreens to power sequence together Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 01/10] dt-bindings: HID: i2c-hid: Add "panel" property to i2c-hid backed touchscreens Douglas Anderson
2023-06-09 15:53 ` Krzysztof Kozlowski
2023-06-07 21:49 ` [PATCH v2 02/10] drm/panel: Check for already prepared/enabled in drm_panel Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 03/10] drm/panel: Add a way for other devices to follow panel state Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 04/10] of: property: fw_devlink: Add a devlink for panel followers Douglas Anderson
2023-06-09 16:10 ` Rob Herring
2023-06-07 21:49 ` [PATCH v2 05/10] HID: i2c-hid: Switch to SYSTEM_SLEEP_PM_OPS() Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 06/10] HID: i2c-hid: Rearrange probe() to power things up later Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 07/10] HID: i2c-hid: Make suspend and resume into helper functions Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 08/10] HID: i2c-hid: Support being a panel follower Douglas Anderson
2023-06-08 5:18 ` kernel test robot
2023-06-08 7:14 ` kernel test robot
2023-06-08 15:10 ` Doug Anderson
2023-06-08 15:36 ` Benjamin Tissoires
2023-06-08 16:42 ` Doug Anderson
2023-06-09 9:27 ` Benjamin Tissoires
2023-06-09 15:01 ` Doug Anderson
2023-06-26 22:49 ` Doug Anderson
2023-07-17 18:15 ` Doug Anderson
2023-07-25 20:41 ` Doug Anderson
2023-07-26 8:07 ` Benjamin Tissoires
2023-06-07 21:49 ` Douglas Anderson [this message]
2023-06-07 21:49 ` [PATCH v2 10/10] arm64: dts: qcom: sc7180: Link trogdor touchscreens to the panels Douglas Anderson
2023-06-08 7:17 ` [PATCH v2 00/10] drm/panel and i2c-hid: Allow panels and touchscreens to power sequence together Maxime Ripard
2023-06-08 14:38 ` Doug Anderson
2023-06-12 16:03 ` Maxime Ripard
2023-06-12 21:13 ` Doug Anderson
2023-06-13 12:06 ` Maxime Ripard
2023-06-13 15:56 ` Doug Anderson
2023-06-21 16:31 ` Doug Anderson
2023-06-23 9:08 ` Maxime Ripard
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