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Driver for TI tlc59116 16 Channel i2c LED driver

Tomi Valkeinen linux-arm-kernel linux-devicetree linux-leds 3 versions – New

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  1. v3 Latest posting 3/30 of 2 patches 0 repliesNew
  2. v3 posting 2/30 of 2 patches 0 repliesSuperseded
  3. v3 posting 1/30 of 2 patches 0 repliesSuperseded

Patches in v3 posting 3/3 No applies recorded yet

None of the 2 patches the cover letter announces are in this archive.

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Cover letter [PATCHv3 0/2] Driver for TI tlc59116 16 Channel i2c LED driver
Quoted 21 lines · Andrew Lunn
Quoted 7 lines

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.

Quoted 5 lines

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.

Quoted 5 lines

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.

Right. TLC591xx has the constant output mode which should be used for GPIO. Perhaps that mode could be always used when the brightness is turned to maximum. I haven't read the spec carefully enough to know if there are some downsides.

Tomi

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Read the cover letter in its thread