pwm: tiecap: Document behaviour of hardware disable

According to David Lechner[1] disabling a tiecap PWM makes the PWM pin
an input. The reported problem is fixed in commit deaeeda2051f
("backlight: pwm_bl: Don't rely on a disabled PWM emiting inactive
state"). Document the behaviour in the driver for future reference.

[1] https://lore.kernel.org/linux-pwm/39a472c0-ba24-de7b-8783-a16a71b172cd@lechnology.com

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: David Lechner <david@lechnology.com>
Link: https://lore.kernel.org/r/20250730080219.183181-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

diff --git a/drivers/pwm/pwm-tiecap.c b/drivers/pwm/pwm-tiecap.c
index d91b2bdc88fce2f43178c1e1064e13c4add49dbf..67cc5e8bdb0ef8ef84f8fb132a7af24a0472b45b 100644 (file)
--- a/drivers/pwm/pwm-tiecap.c
+++ b/drivers/pwm/pwm-tiecap.c
@@ -3,6 +3,10 @@
  * ECAP PWM driver
  *
  * Copyright (C) 2012 Texas Instruments, Inc. - https://www.ti.com/
+ *
+ * Hardware properties:
+ * - On disable the PWM pin becomes an input, so the behaviour depends on
+ *   external wiring.
  */
 
 #include <linux/module.h>