[12/17] staging: nuc-wmi: better detect NUC6/NUC7 devices
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Message ID bca097a3ce2ab35fcd38eb3abdc8090c2c531048.1621161037.git.mchehab+huawei@kernel.org
State New, archived
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Series
  • Add an experimental driver for Intel NUC leds
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Commit Message

Mauro Carvalho Chehab May 16, 2021, 10:53 a.m. UTC
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/staging/nuc-led/nuc-wmi.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

Patch
diff mbox series

diff --git a/drivers/staging/nuc-led/nuc-wmi.c b/drivers/staging/nuc-led/nuc-wmi.c
index 5bc4dcec3ea8..1a6e2b17c888 100644
--- a/drivers/staging/nuc-led/nuc-wmi.c
+++ b/drivers/staging/nuc-led/nuc-wmi.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;