From: David Lin <dtwlin@google.com>
To: corbet@lwn.net, rpurdie@rpsys.net, jacek.anaszewski@gmail.com,
pavel@ucw.cz, hdegoede@redhat.com, mark.rutland@arm.com,
tony.makkiel@daqri.com, linz@li-pro.net
Cc: robh@kernel.org, romlem@google.com, joelaf@google.com,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-leds@vger.kernel.org, David Lin <dtwlin@google.com>
Subject: [PATCH 2/3] leds: Add the LED_BRIGHTNESS_FAST flag
Date: Sun, 30 Apr 2017 14:37:00 -0700 [thread overview]
Message-ID: <20170430213701.12297-3-dtwlin@google.com> (raw)
In-Reply-To: <20170430213701.12297-1-dtwlin@google.com>
This patch adds the LED_BRIGHTNESS_FAST flag to allow the driver to
indicate that the brightness_set() callback is implemented on a fastpath
so that the LED core may choose to for example use a hrtimer to
implement the duration of a trigger for better timing accuracy.
Suggested-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: David Lin <dtwlin@google.com>
---
Documentation/leds/leds-class.txt | 5 +++++
include/linux/leds.h | 1 +
2 files changed, 6 insertions(+)
diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
index 836cb16d6f09..70d7a3dca621 100644
--- a/Documentation/leds/leds-class.txt
+++ b/Documentation/leds/leds-class.txt
@@ -80,6 +80,11 @@ flag must be set in flags before registering. Calling
led_classdev_notify_brightness_hw_changed on a classdev not registered with
the LED_BRIGHT_HW_CHANGED flag is a bug and will trigger a WARN_ON.
+Optionally, the driver may choose to register with the LED_BRIGHTNESS_FAST flag.
+This flag indicates that the driver implements the brightness_set() callback
+function using a fastpath so the LED core can use hrtimer if the driver requires
+high precision for the trigger timing.
+
Hardware accelerated blink of LEDs
==================================
diff --git a/include/linux/leds.h b/include/linux/leds.h
index f9d10a9efcbe..78d2880ccd39 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -49,6 +49,7 @@ struct led_classdev {
#define LED_HW_PLUGGABLE BIT(19)
#define LED_PANIC_INDICATOR BIT(20)
#define LED_BRIGHT_HW_CHANGED BIT(21)
+#define LED_BRIGHTNESS_FAST BIT(22)
/* set_brightness_work / blink_timer flags, atomic, private. */
unsigned long work_flags;
--
2.13.0.rc0.306.g87b477812d-goog
next prev parent reply other threads:[~2017-04-30 21:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-30 21:36 [PATCH 0/3] led: ledtrig-transient: add support for hrtimer David Lin
2017-04-30 21:36 ` [PATCH 1/3] leds: Replace flags bit shift with BIT() macros David Lin
2017-05-08 20:24 ` Jacek Anaszewski
2017-04-30 21:37 ` David Lin [this message]
2017-04-30 21:37 ` [PATCH 3/3] led: ledtrig-transient: add support for hrtimer David Lin
2017-05-08 20:25 ` Jacek Anaszewski
2017-05-04 0:28 ` [PATCH 0/3] " David Lin
2017-05-08 21:06 ` Pavel Machek
2017-05-09 20:43 ` Jacek Anaszewski
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