Re: [PATCH 1/2] backlight: lm3630a: add an enable gpio for the HWEN pin

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, 10 Sep 2019 11:21:56 +0100
Daniel Thompson <daniel.thompson@xxxxxxxxxx> wrote:

[...]
> > > Is this needed?
> > > 
> > > This is a remove path, not a power management path, and we have no idea
> > > what the original status of the pin was anyway?
> > >   
> > 
> > Looking at Ishdn on page 5 of the datasheet, switching it off everytime
> > possible seems not needed. We would need to call chip_init() everytime
> > we enable the gpio or live with default values.
> > Therefore I did decide to not put it into any power management path.
> > But switching it on and not switching it off feels so unbalanced.   
> 
> Either the power consumed by the controller when strings aren't lit up
> matters, in which case the driver should implement proper power
> management or it doesn't matter and changing the pin state isn't needed.
> 
> I'm happy with either of the above but this looks like a third way,
> where eager users could hack in a bit of extra power management by
> forcing drivers to unbind. 
> 
I think I will take the simple way. I am quite sure that the power
consumption with HWEN on and leds off does not matter. If someone
later comes up and finds out that I misread the datasheet, things
are prepared to be improved.
At least the hardware can be properly described in the devicetree.

Regards,
Andreas

Attachment: pgpzGv2V7mqcL.pgp
Description: OpenPGP digital signature

_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Index of Archives]     [Linux DRI Users]     [Linux Intel Graphics]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux