linux-kernel - [PATCH] platform/chrome: wilco_ec: Fix keyboard backlight probing

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Date:   Tue,  7 Jan 2020 11:24:21 -0700
From:   Daniel Campello <campello@...omium.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Daniel Campello <campello@...omium.org>,
        Nick Crews <ncrews@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Benson Leung <bleung@...omium.org>
Subject: [PATCH] platform/chrome: wilco_ec: Fix keyboard backlight probing

The EC on the Wilco platform responds with 0xFF to commands related to
the keyboard backlight on the absence of a keyboard backlight module.
This change allows the EC driver to continue loading even if the
backlight module is not present.

Signed-off-by: Daniel Campello <campello@...omium.org>
---

 .../platform/chrome/wilco_ec/keyboard_leds.c  | 28 +++++++++++++------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/platform/chrome/wilco_ec/keyboard_leds.c b/drivers/platform/chrome/wilco_ec/keyboard_leds.c
index bb0edf51dfda..5731d1b60e28 100644
--- a/drivers/platform/chrome/wilco_ec/keyboard_leds.c
+++ b/drivers/platform/chrome/wilco_ec/keyboard_leds.c
@@ -73,13 +73,6 @@ static int send_kbbl_msg(struct wilco_ec_device *ec,
 		return ret;
 	}

-	if (response->status) {
-		dev_err(ec->dev,
-			"EC reported failure sending keyboard LEDs command: %d",
-			response->status);
-		return -EIO;
-	}
-
 	return 0;
 }

@@ -87,6 +80,7 @@ static int set_kbbl(struct wilco_ec_device *ec, enum led_brightness brightness)
 {
 	struct wilco_keyboard_leds_msg request;
 	struct wilco_keyboard_leds_msg response;
+	int ret;

 	memset(&request, 0, sizeof(request));
 	request.command = WILCO_EC_COMMAND_KBBL;
@@ -94,7 +88,18 @@ static int set_kbbl(struct wilco_ec_device *ec, enum led_brightness brightness)
 	request.mode    = WILCO_KBBL_MODE_FLAG_PWM;
 	request.percent = brightness;

-	return send_kbbl_msg(ec, &request, &response);
+	ret = send_kbbl_msg(ec, &request, &response);
+	if (ret < 0)
+		return ret;
+
+	if (response.status) {
+		dev_err(ec->dev,
+			"EC reported failure sending keyboard LEDs command: %d",
+			response.status);
+		return -EIO;
+	}
+
+	return 0;
 }

 static int kbbl_exist(struct wilco_ec_device *ec, bool *exists)
@@ -140,6 +145,13 @@ static int kbbl_init(struct wilco_ec_device *ec)
 	if (ret < 0)
 		return ret;

+	if (response.status) {
+		dev_err(ec->dev,
+			"EC reported failure sending keyboard LEDs command: %d",
+			response.status);
+		return -EIO;
+	}
+
 	if (response.mode & WILCO_KBBL_MODE_FLAG_PWM)
 		return response.percent;

--
2.24.1.735.g03f4e72817-goog