From: Tony Lindgren <tony@atomide.com>
To: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: "Benoît Cousson" <bcousson@baylibre.com>,
"Rob Herring" <robh+dt@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Russell King" <linux@armlinux.org.uk>,
linux-omap@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, letux-kernel@openphoenux.org
Subject: Re: [PATCH 2/3] DT: EVM: add LEDs
Date: Wed, 28 Sep 2016 09:12:03 -0700 [thread overview]
Message-ID: <20160928161202.sv2xtcotypex2aop@atomide.com> (raw)
In-Reply-To: <22676D6D-0669-41BC-B45D-FCC07E8C14CB@goldelico.com>
* H. Nikolaus Schaller <hns@goldelico.com> [160928 08:29]:
>
> > Am 28.09.2016 um 17:12 schrieb Tony Lindgren <tony@atomide.com>:
> >
> > * H. Nikolaus Schaller <hns@goldelico.com> [160927 23:50]:
> >> Hi,
> >>
> >>> Am 28.09.2016 um 05:37 schrieb Tony Lindgren <tony@atomide.com>:
> >>>
> >>> * H. Nikolaus Schaller <hns@goldelico.com> [160927 13:11]:
> >>>>> Am 27.09.2016 um 21:49 schrieb Tony Lindgren <tony@atomide.com>:
> >>>>> How about this for defaults:
> >>>>>
> >>>>> - heartbeat for led3
> >>>>> - cpu0 for led4
> >>>>> - cpu1 for led5
> >>>>
> >>>> Good idea. Will try.
> >>>>
> >>>> What I don't exactly know is if these gpios based on an I2C-expander
> >>>> can handle cpu activity triggers or if they are locked up if this i2c
> >>>> processing triggers another cpu activity...
> >>>
> >>> Oh right, if the GPIOs are on the i2c bus
> >>
> >> yes, they are all gpio9 which is the tca6424 on i2c5.
> >>
> >>> it's probably not a good
> >>> idea :) Or at least will be inaccurate if the bus can sleep.
> >>
> >> I have tested a little by writing to /sys/class/leds/.../trigger.
> >>
> >> If I make one LED trigger by "cpu0" it is always on and if I make
> >> a second one triggered by "cpu1" the heartbeat becomes irregular.
> >>
> >> So indeed this does not work.
> >
> > So should we just leave the default trigger unpopulated then?
>
> It is a matter of taste and something not easy to decide...
>
> And everything can be changed from user-space by some script
> running during the boot process to a more meaningful setting.
>
> So the initial setting doesn't matter really much.
>
> Having some of the LEDs as heartbeat gives an (additional)
> feedback that the kernel has booted.
>
> We could even take led1, led3 and led5 as heartbeat and the other
> two as default-on. Would give a nice pattern showing that the LEDs
> are not broken...
>
> So let me know how you would like to have it and I add it to a PATCH v2.
Up to you for the blinking, I'm fine with the original version
too unless you feel like changing it.
Regards,
Tony
next prev parent reply other threads:[~2016-09-28 16:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 5:26 [PATCH 0/3] ARM: dts: omap5 uevm: add LEDs, USR1 button and EEPROM H. Nikolaus Schaller
2016-09-27 5:26 ` [PATCH 1/3] DT: EVM: add EEPROM H. Nikolaus Schaller
2016-09-27 5:26 ` [PATCH 2/3] DT: EVM: add LEDs H. Nikolaus Schaller
2016-09-27 19:49 ` Tony Lindgren
2016-09-27 20:10 ` H. Nikolaus Schaller
2016-09-28 3:37 ` Tony Lindgren
2016-09-28 6:49 ` H. Nikolaus Schaller
2016-09-28 15:12 ` Tony Lindgren
2016-09-28 15:28 ` H. Nikolaus Schaller
2016-09-28 16:12 ` Tony Lindgren [this message]
2016-09-29 5:14 ` Rob Herring
2016-09-29 5:18 ` H. Nikolaus Schaller
2016-09-29 5:20 ` H. Nikolaus Schaller
2016-09-27 5:26 ` [PATCH 3/3] DT: EVM: add USR1 button H. Nikolaus Schaller
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