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From: Kenny Levinsen <kl@kl.wtf>
To: Jiri Kosina <jikos@kernel.org>,
	Dmitry Torokhov <dtor@chromium.org>,
	Benjamin Tissoires <benjamin.tissoires@redhat.com>,
	Douglas Anderson <dianders@chromium.org>,
	Hans de Goede <hdegoede@redhat.com>,
	Maxime Ripard <mripard@kernel.org>,
	Kai-Heng Feng <kai.heng.feng@canonical.com>,
	Johan Hovold <johan+linaro@kernel.org>,
	linux-input@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Radoslaw Biernacki <rad@chromium.org>,
	Lukasz Majczak <lma@chromium.org>
Cc: Kenny Levinsen <kl@kl.wtf>
Subject: [PATCH v2 3/3] HID: i2c-hid: Align i2c_hid_set_power() retry with HID descriptor read
Date: Tue, 23 Apr 2024 14:07:55 +0200
Message-ID: <20240423122518.34811-4-kl@kl.wtf>
In-Reply-To: <20240423122518.34811-1-kl@kl.wtf>
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The retry for HID descriptor and for power commands deals with the same
device quirk, so align the two.

Signed-off-by: Kenny Levinsen <kl@kl.wtf>
---
 drivers/hid/i2c-hid/i2c-hid-core.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 252ccb3b71d1..749c0c036adb 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -391,25 +391,21 @@ static int i2c_hid_set_power(struct i2c_hid *ihid, int power_state)
 	i2c_hid_dbg(ihid, "%s\n", __func__);
 
 	/*
-	 * Some devices require to send a command to wakeup before power on.
-	 * The call will get a return value (EREMOTEIO) but device will be
-	 * triggered and activated. After that, it goes like a normal device.
+	 * Some STM-based devices need 400µs after a rising clock edge to wake
+	 * from deep sleep, which in turn means that our first command will
+	 * fail EREMOTEIO. Certain Weida Tech devices also need this wake-up.
+	 * Retry the command in this case.
 	 */
-	if (power_state == I2C_HID_PWR_ON) {
+	ret = i2c_hid_set_power_command(ihid, power_state);
+	if (ret == -EREMOTEIO && power_state == I2C_HID_PWR_ON) {
+		usleep_range(400, 500);
 		ret = i2c_hid_set_power_command(ihid, I2C_HID_PWR_ON);
-
-		/* Device was already activated */
-		if (!ret)
-			goto set_pwr_exit;
 	}
 
-	ret = i2c_hid_set_power_command(ihid, power_state);
 	if (ret)
 		dev_err(&ihid->client->dev,
 			"failed to change power setting.\n");
 
-set_pwr_exit:
-
 	/*
 	 * The HID over I2C specification states that if a DEVICE needs time
 	 * after the PWR_ON request, it should utilise CLOCK stretching.
-- 
2.44.0