From: Andrew Lunn <andrew@lunn.ch>
To: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: cooloney@gmail.com, rpurdie@rpsys.net, "R,
Vignesh" <vigneshr@ti.com>,
linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
linux ARM <linux-arm-kernel@lists.infradead.org>,
kaloz@openwrt.org, Matthew.Fatheree@belkin.com,
Sekhar Nori <nsekhar@ti.com>
Subject: Re: [PATCHv3 0/2] Driver for TI tlc59116 16 Channel i2c LED driver
Date: Tue, 20 Jan 2015 14:26:13 +0100 [thread overview]
Message-ID: <20150120132613.GJ2938@lunn.ch> (raw)
In-Reply-To: <54BE258A.10808@ti.com>
> I'm not familiar with the LED/PWM frameworks, so I want to summarize our
> use case and how I guess this should be done:
>
> We use the TLC59108 to provide backlight to a LCD, but in addition to
> that, it is used as a GPIO expander (or GPO, as it cannot do input). In
> your earlier patch versions there were some 'gpio' leftovers. Does your
> board have such GPIO use also?
No, only LEDs.
> So my current thinking is that TLC591xx should be a LED driver (as it
> sounded to me that PWM is not quite suitable for it). On top of that, we
> need generic 'led-backlight' and 'led-gpio' drivers, each of which uses
> the given LED driver to do the hardware manipulation, and they expose a
> backlight device and gpio device, respectively.
That sounds sensible. led-backlight seems to be mostly implemented
already via the led trigger code. Adding a minimal backlight_ops does
not look too hard. You might also be able to do some cleanup of the
other led based backlight drivers.
led-gpio looks like more work, but i don't see why it should not be
possible. One thing i do need to check is that if the brightness is
set to 255 the output is not set to 255/256 on and you have a regular
glitch. For an LED that does not really matter, but for GPIO it would
not be good.
Andrew
next prev parent reply other threads:[~2015-01-20 13:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-14 23:15 [PATCHv3 0/2] Driver for TI tlc59116 16 Channel i2c LED driver Andrew Lunn
2015-01-14 23:15 ` [PATCHv3 1/2] leds: tlc59116: Document binding for the TI " Andrew Lunn
2015-01-14 23:15 ` [PATCHv3 2/2] leds: tlc59116: Driver " Andrew Lunn
2015-01-16 14:52 ` [PATCHv3 0/2] Driver for TI tlc59116 " Tomi Valkeinen
[not found] ` <54B9259C.3070403-l0cyMroinI0@public.gmane.org>
2015-01-16 15:55 ` Andrew Lunn
2015-01-16 17:50 ` R, Vignesh
2015-01-16 19:10 ` Andrew Lunn
2015-01-16 19:17 ` Andrew Lunn
2015-01-20 9:53 ` Tomi Valkeinen
2015-01-20 13:26 ` Andrew Lunn [this message]
[not found] ` <20150120132613.GJ2938-g2DYL2Zd6BY@public.gmane.org>
2015-01-20 13:32 ` Tomi Valkeinen
2015-01-20 13:40 ` Andrew Lunn
2015-01-20 13:33 ` Geert Uytterhoeven
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