From: Johan Hovold <jhovold@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Johan Hovold <jhovold@gmail.com>,
Jonathan Cameron <jic23@cam.ac.uk>, Rob Landley <rob@landley.net>,
Richard Purdie <rpurdie@rpsys.net>,
Samuel Ortiz <sameo@linux.intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
Arnd Bergmann <arnd@arndb.de>,
Andrew Morton <akpm@linux-foundation.org>,
Mark Brown <broonie@opensource.wolfsonmicro.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-iio@vger.kernel.org, devel@driverdev.osuosl.org,
linux-fbdev@vger.kernel.org
Subject: Re: [PATCH v2 2/4] iio: add LM3533 ambient light sensor driver
Date: Fri, 18 May 2012 19:57:42 +0200 [thread overview]
Message-ID: <20120518175742.GA12894@localhost> (raw)
In-Reply-To: <4FB68809.2010009@kernel.org>
On Fri, May 18, 2012 at 06:34:01PM +0100, Jonathan Cameron wrote:
> On 05/18/2012 01:27 PM, Johan Hovold wrote:
[...]
> > I really think that this should remain a device specific attribute as I
> > originally suggested. It's an integration parameter that needs to be set
> > precisely depending on the actual hardware setup (which analog light
> > sensor and other external components).
> Then it shouldn't be exposed to userspace. If there is reason to vary
> it from userspace then it is a calibration parameter and should be
> treated like the other ones we have, if not it should be done from
> dt or platform data.
> >
> > The lm3533 also supports two types of light sensors: pwm- and analog-
> > output ones. The resistor select settings only applies when in analog
> > mode as the input is always high impedance otherwise. Thus a generic
> > attribute (such as calibscale or hardware gain) shouldn't be used as it
> > will have no effect whatsoever in PWM-mode.
> >
> > I'm thus back at my original proposal, albeit with a different name (I
> > think a lot of this discussion could have been avoided had I not
> > misnamed the parameter "gain"):
> >
> > What: /sys/bus/iio/devices/iio:deviceX/r_select
> > Description:
> > Set the ALS internal pull-down resistor for analog input mode
> > (1..127), such that,
> >
> > R_als = 200000 / r_select (ohm)
> >
> > This setting is ignored in PWM-mode (input is always high
> > impedance in PWM-mode).
> >
> > I don't think much is gained from using ohm as the unit: it just adds
> > complexity and the selected resistor setting will likely not match the
> > input value anyway. It's better that the chip integrators have full
> > control over which resistor setting is actually used so that it matches
> > external components.
> This smacks of something that should never be exposed to users.
> I'd hide it away in platform data.
Fair enough. I'll drop the sysfs param and submit a patch for mfd-next
which adds r_select to the platform data.
Thanks,
Johan
next prev parent reply other threads:[~2012-05-18 17:57 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-20 15:30 [PATCH 0/4] mfd: add LM3533 lighting-power chip driver Johan Hovold
2012-04-20 15:30 ` [PATCH 1/4] mfd: add LM3533 lighting-power core driver Johan Hovold
2012-04-26 12:41 ` Mark Brown
2012-05-03 10:15 ` Johan Hovold
2012-05-03 10:22 ` Johan Hovold
2012-04-20 15:30 ` [PATCH 2/4] misc: add LM3533 ambient light sensor driver Johan Hovold
2012-04-20 15:57 ` Greg Kroah-Hartman
2012-04-20 17:28 ` Johan Hovold
2012-04-20 17:37 ` Greg Kroah-Hartman
2012-04-26 11:52 ` Johan Hovold
2012-04-20 15:30 ` [PATCH 3/4] leds: add LM3533 LED driver Johan Hovold
2012-04-20 16:10 ` Arnd Bergmann
2012-04-20 16:45 ` Johan Hovold
2012-04-20 15:30 ` [PATCH 4/4] backlight: add LM3533 backlight driver Johan Hovold
2012-05-03 10:26 ` [PATCH v2 0/4] mfd: add LM3533 lighting-power chip driver Johan Hovold
2012-05-03 10:26 ` [PATCH v2 1/4] mfd: add LM3533 lighting-power core driver Johan Hovold
2012-05-03 10:38 ` Mark Brown
2012-05-03 11:28 ` Johan Hovold
2012-05-03 11:38 ` Mark Brown
2012-05-03 15:00 ` Johan Hovold
2012-05-03 15:24 ` Mark Brown
2012-05-03 16:54 ` Johan Hovold
2012-05-03 16:57 ` Mark Brown
2012-05-03 17:14 ` Johan Hovold
2012-05-03 17:23 ` Mark Brown
2012-05-03 17:31 ` Johan Hovold
2012-05-09 14:42 ` Samuel Ortiz
2012-05-10 12:07 ` Johan Hovold
2012-05-10 12:11 ` [PATCH 1/2] mfd: lm3533: add boost frequency and ovp to platform data Johan Hovold
2012-05-10 12:11 ` [PATCH 2/2] mfd: lm3533: remove boost attributes Johan Hovold
2012-05-10 17:18 ` [PATCH 0/2] mfd: lm3533: update max-current interface Johan Hovold
2012-05-10 17:18 ` [PATCH 1/2] mfd: lm3533: remove unused max-current function Johan Hovold
2012-05-10 17:18 ` [PATCH 2/2] mfd: lm3533: use SI-units for max-current interface Johan Hovold
2012-05-11 13:32 ` [PATCH v2 1/4] mfd: add LM3533 lighting-power core driver Samuel Ortiz
2012-05-03 10:26 ` [PATCH v2 2/4] iio: add LM3533 ambient light sensor driver Johan Hovold
2012-05-03 11:40 ` Jonathan Cameron
2012-05-03 16:36 ` Johan Hovold
2012-05-08 13:47 ` Jonathan Cameron
2012-05-15 16:44 ` Johan Hovold
2012-05-15 20:00 ` Jonathan Cameron
2012-05-16 13:05 ` Johan Hovold
2012-05-16 14:21 ` Jonathan Cameron
2012-05-18 12:27 ` Johan Hovold
2012-05-18 17:34 ` Jonathan Cameron
2012-05-18 17:57 ` Johan Hovold [this message]
2012-05-19 8:04 ` Jonathan Cameron
2012-05-15 16:46 ` [PATCH v3] iio: add LM3533 ambient-light-sensor driver Johan Hovold
2012-05-15 19:27 ` Andrew Morton
2012-05-15 20:00 ` Johan Hovold
2012-05-15 20:16 ` Jonathan Cameron
2012-05-18 13:07 ` [PATCH v4] " Johan Hovold
2012-05-19 8:48 ` Jonathan Cameron
2012-05-19 16:30 ` Johan Hovold
2012-05-19 13:26 ` Jonathan Cameron
2012-05-21 9:50 ` Johan Hovold
2012-05-21 16:37 ` Jonathan Cameron
2012-05-21 22:07 ` Johan Hovold
2012-05-22 7:13 ` Jonathan Cameron
2012-05-22 9:09 ` Johan Hovold
2012-05-22 9:15 ` Jonathan Cameron
2012-05-22 7:45 ` Michael Hennerich
2012-05-22 7:49 ` Jonathan Cameron
2012-05-22 8:11 ` Michael Hennerich
2012-05-22 8:20 ` Jonathan Cameron
2012-05-21 12:18 ` [PATCH v5] " Johan Hovold
2012-05-22 9:19 ` Jonathan Cameron
2012-05-22 9:40 ` Johan Hovold
2012-05-22 13:55 ` Greg Kroah-Hartman
2012-06-05 4:11 ` Greg Kroah-Hartman
2012-05-03 10:26 ` [PATCH v2 3/4] leds: add LM3533 LED driver Johan Hovold
2012-05-03 10:43 ` Mark Brown
2012-05-03 11:50 ` Johan Hovold
2012-05-03 14:51 ` Mark Brown
2012-05-03 16:46 ` Johan Hovold
2012-05-10 18:27 ` [PATCH v3] " Johan Hovold
2012-05-10 18:48 ` Andrew Morton
2012-05-11 9:54 ` Johan Hovold
2012-05-11 22:24 ` Andrew Morton
2012-05-14 10:25 ` Johan Hovold
2012-05-14 10:31 ` [PATCH v4] " Johan Hovold
2012-05-03 10:26 ` [PATCH v2 4/4] backlight: add LM3533 backlight driver Johan Hovold
2012-05-10 18:29 ` [PATCH v3] " Johan Hovold
2012-05-15 19:13 ` [PATCH v4] " Johan Hovold
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