GTA03 LED controller: LP5521

Flemming Richter Mikkelsen quatrox at
Tue Jan 6 16:31:22 CET 2009

Sorry. This was intended for the list, not only to werner.

On Tue, Jan 6, 2009 at 16:27,  <quatrox at> wrote:
> On 2008-11-18, Werner Almesberger <werner at> wrote:
>> Andy Green wrote:
>>> There's a choice about using the userland i2c stuff to access the
>>> storage for the program or having a driver at all.
>> All in user space. Even better !
>>>  If we have a driver,
>>> we probably make a /sys you dump the LED state machine binary "program"
>>> down to set it.  That's probably as far as we should take it if even
>>> that far.
>> Yup, or hex, like the driver Andrzej mentioned.
>>> What would guide us towards having a driver is if kernelside could want
>>> to use the LEDs itself, eg, to indicate panic.
>> Panic indication would seem a valid excuse for having something in
>> the kernel, yes. But that could also be just a "panic-only" driver.
>> It may have to violate quite a few rules anyway, to be able to get
>> through to the LED controller when the system is in trouble.
>> We don't have any easily GPIO-accessible LED, do we ?
> That would be easy:
> Assuming all the LED's are directly connected to the LED driver,
> one can also route a GPIO pin from the CPU directly to the LED
> (for use in cases of kernel panic, etc).

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