lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 09 Apr 2012 14:20:47 -0600 From: Shuah Khan <shuahkhan@...il.com> To: Dmitry Torokhov <dmitry.torokhov@...il.com> Cc: shuahkhan@...il.com, Andrew Morton <akpm@...ux-foundation.org>, neilb@...e.de, rpurdie@...ux.intel.com, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH RESEND] LEDS-One-Shot-Timer-Trigger-implementation On Mon, 2012-04-09 at 11:45 -0700, Dmitry Torokhov wrote: > On Mon, Apr 09, 2012 at 12:16:05PM -0600, Shuah Khan wrote: > > On Mon, 2012-04-09 at 10:37 -0700, Dmitry Torokhov wrote: > > > On Mon, Apr 09, 2012 at 10:55:49AM -0600, Shuah Khan wrote: > > > > On Sat, 2012-04-07 at 14:56 -0700, Dmitry Torokhov wrote: > > > > > Hi Shuah, > > > > > > > > > > On Sat, Apr 07, 2012 at 08:13:44AM -0600, Shuah Khan wrote: > > > > > > > > > > > > > > +This feature will help implement vibrate functionality which requires one > > > > > > > > +time activation of vibrate mode without a continuous vibrate on/off cycles. > > > > > > > > > > > > > > They make vibrating LED? ;) > > > > > > > > > > > > > > What's going on here? You're proposing to repurpose the LEDs code to > > > > > > > drive vibration devices? Or some devices couple a LED with a vibration > > > > > > > device? > > > > > > > > > > > > I owe you filling in the blanks type explanation. Let me describe the > > > > > > use-case I am trying to address first. Vibrater function on phones is > > > > > > implemented using PWM pins on SoC or PMIC. When there is no such > > > > > > hardware present, a software solution is needed. Currently two drivers > > > > > > timed-gpio and timed-output (under staging/android in Linux 3.3) > > > > > > together implement the software vibrate feature. The main functionality > > > > > > it implements is the one time enables of timer to prevent user space > > > > > > crashes leaving the phone in vibrate mode causing the battery to drain. > > > > > > leds as it is implemented currently, is not suitable to address this > > > > > > use-case as it doesn't support one time enables. > > > > > > > > > > So why do not you use memoryless force feedback framework that other > > > > > devices use (see drivers/input/misc/*vibra.c drivers). > > > > > > > > > > > > > Dimitry, > > > > > > > > I took a look at these vibra* drivers. The three vibrate drivers are > > > > chip-set specific. The use-case I have is a non-chip set approach to > > > > address the use-case when vibrate hardware is not present. Are you > > > > envisioning a generic approach using ff-memoryless infrastructure? > > > > > > Shuah, > > > > > > I guess I am confused now. You need some form of hardware to make your > > > device to vibrate. > > > > > > What exactly are you trying to do? Are you trying to: > > > > > > 1. activate vibration on devices that can actually do it using LED > > > interface, or > > > > > > 2. use LEDs as an alternative to vibrate on devices that can't > > > physically vibrate? > > > > > > Thanks. > > > > What I meant by generic approach is a higher level interface that is not > > tied too closely to the underlying hardware. Similar to the leds-pwm.c > > and leds-gpio.c handle gpio and pwm based leds. The vibrate hardware in > > my sue-case is a gpio based and could pwm based on some phones. > > Ok, so you need to add drivers/input/misc/gpio-vibrate.c and pwm-vibrate.c > and then use FF to activate them. This way we have all vibrate > implementation use one subsystem instead of splitting between > input/led/whatever else people could come up with. > > Thanks. > Dmitry, It is unfortunate that we have these two infrastructures evolve that has a lot of overlap. Let me summarize the two alternatives first so we get a feel for the work involved to address this use-case using ff and leds frameworks: Alternative 1: using leds infrastructure Add new kernel interface to support one time enables. This will enable existing gpio and pwm drivers to be used to implement vibrate. Alternative 2: using ff infrastructure Add new drivers gpio and pwm that use existing one time enable to implement vibrate in a generic way. Does this sound right? From a quick glance it sounds like we can get to the end goal quicker and in a simpler way with Alternative 1. However, I might be missing longterm view. Any other alternatives we could explore? -- Shuah -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists