From: Jacek Anaszewski <jacek.anaszewski@gmail.com>
To: Pavel Machek <pavel@ucw.cz>, David Lin <dtwlin@google.com>
Cc: corbet@lwn.net, rpurdie@rpsys.net, hdegoede@redhat.com,
mark.rutland@arm.com, tony.makkiel@daqri.com, linz@li-pro.net,
robh@kernel.org, romlem@google.com, joelaf@google.com,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-leds@vger.kernel.org
Subject: Re: [PATCH 0/3] led: ledtrig-transient: add support for hrtimer
Date: Tue, 9 May 2017 22:43:45 +0200 [thread overview]
Message-ID: <d9f9dd95-b5c4-8447-1391-594b461f805c@gmail.com> (raw)
In-Reply-To: <20170508210602.GA7260@amd>
On 05/08/2017 11:06 PM, Pavel Machek wrote:
> On Sun 2017-04-30 14:36:58, David Lin wrote:
>> Hi,
>>
>> These patch series add the LED_BRIGHTNESS_FAST flag support for
>> ledtrig-transient to use hrtimer so that platforms with high-resolution timer
>> support can have better accuracy in the trigger duration timing. The need for
>> this support is driven by the fact that Android has removed the timed_ouput [1]
>> and is now using led-trigger for handling vibrator control which requires the
>> timer to be accurate up to a millisecond. However, this flag support would also
>> allow hrtimer to co-exist with the ktimer without causing warning to the
>> existing drivers [2].
>
> Yes, and objection still stands: You are misusing LED subsystem for
> vibration motors. We already have support for haptic feedback in input
> subsystem.
Regardless of whether it is a misuse or not (ledtrig-transient
documentation suggests that it is one of use cases) we have to keep
it as it has been around for a long time and it has userspace users [0].
Moreover there seems to be broad consensus about it among kernel
people [1].
[0]
https://android.googlesource.com/platform%2Fhardware%2Flibhardware/+/61701df363310a5cbd95e3e1638baa9526e42c9b
[1] https://patchwork.kernel.org/patch/8664831/
--
Best regards,
Jacek Anaszewski
prev parent reply other threads:[~2017-05-09 20:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-30 21:36 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 ` [PATCH 2/3] leds: Add the LED_BRIGHTNESS_FAST flag David Lin
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 [this message]
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