[v2,13/17] leds: leds-nuc: better detect NUC6/NUC7 devices

Message ID 29e9896e41eec83e8e775295d92fe3034735c792.1621349814.git.mchehab+huawei@kernel.org
State New
Headers show
Series
  • Adding support for controlling the leds found on Intel NUC
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Commit Message

Mauro Carvalho Chehab May 18, 2021, 3:09 p.m.
There's no documented way to detect if the WMI API is valid,
as, when it is not valid, it just returns 4 zeros.

However, as having a value of 0x00 for the blinking state
is not valid, we can check for it at detection time, in
order to disable LEDs control on devices that won't
support it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 drivers/leds/leds-nuc.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

Patch

diff --git a/drivers/leds/leds-nuc.c b/drivers/leds/leds-nuc.c
index 6aa0bf16c8b7..af57f54cfb05 100644
--- a/drivers/leds/leds-nuc.c
+++ b/drivers/leds/leds-nuc.c
@@ -312,6 +312,13 @@  static int nuc_wmi_query_leds_nuc6(struct device *dev)
 		return ret;
 	}
 
+	/*
+	 * Detect if NUC6/NUC7 supports the WMI API by checking the
+	 * returned blink state, as valid values range from 0x01 to 0x07.
+	 */
+	if (output[1] == 0x00)
+		return -ENODEV;
+
 	led = &priv->led[priv->num_leds];
 	led->id = POWER_LED;
 	led->color_type = LED_BLUE_AMBER;
@@ -325,6 +332,14 @@  static int nuc_wmi_query_leds_nuc6(struct device *dev)
 		dev_warn(dev, "Get S0 Ring: error %d\n", ret);
 		return ret;
 	}
+
+	/*
+	 * Detect if NUC6/NUC7 supports the WMI API by checking the
+	 * returned blink state, as valid values range from 0x01 to 0x07.
+	 */
+	if (output[1] == 0x00)
+		return -ENODEV;
+
 	led = &priv->led[priv->num_leds];
 	led->id = RING_LED;
 	led->color_type = LED_BLUE_AMBER;