From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Whitten Subject: Re: [PATCH/RFC v2] leds: trigger: Introduce a NETDEV trigger Date: Wed, 6 Dec 2017 20:07:41 +0000 Message-ID: References: <1512472751-10928-1-git-send-email-ben.whitten@lairdtech.com> <6cad314f-3cef-ec74-b55e-cccae28da4ab@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: rpurdie@rpsys.net, pavel@ucw.cz, linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Jacek Anaszewski Return-path: In-Reply-To: <6cad314f-3cef-ec74-b55e-cccae28da4ab@gmail.com> Sender: linux-leds-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi Jacek, On 5 December 2017 at 20:38, Jacek Anaszewski wrote: > Hi Ben, > > On 12/05/2017 12:19 PM, Ben Whitten wrote: >> From: Ben Whitten >> >> The patch was converted to led_blink_oneshot, in doing so we find that the >> behaviour has changed. As I dont want to break 'userspace' led behaviour this >> patch shouldn't be merged as is. Open to suggestions. >> >> Given an interval of 50ms and heavy throughput, the previous implementation >> produced a blink with 100ms period and 50% dutycycle. The led_blink_oneshot >> version produces a blink with 140ms period and 57% dutycycle. > > Please check if the LED class driver you're testing the trigger with > implements blink_set op. If yes it would be good to check if it doesn't > align the delay intervals to the hardware capabilities instead of > failing and relying on a LED core software blink fallback. The led are using gpio-led set from device tree on an embedded system, sama5 based. So as far as I can tell blink_op is NULL in this case and it then relies on software for the blink in the form of timers. I assume its the jiffies playing a part here, taking a jiffy or two to queue up a flash may add 10ms to the desired 50ms delay_on/delay_off that I am seeing. Then the extra time may be due to the stats workqueue not aligning with the blink timer to kick it off again. Best regards, Ben