On Fri, Feb 20, 2015 at 5:24 PM, Jens Thiele <ka...@karme.de> wrote:
> Hans de Goede <hdego...@redhat.com> writes:
>
>> Hi,
>>
>> On 19-02-15 22:09, Jens Thiele wrote:
>>> would dpms-like functionality work using simplefb with gpio_backlight
>>> (CONFIG_BACKLIGHT_GPIO) if one provides correct information in the .dts
>>> file?
>>
>> I believe that that would depend on your desktop environments, the
>> sysfs backlight interface is typically used by the desktop environment
>> and not by X itself, so if the desktop environment not only makes X server
>> calls to do dpms but also sets the backlight off then yes it should work.
>
> ah, yes thanks!
> would have to take a closer look (again) - but yes, afair x fbdev used
> something like:
> int fd=open("/dev/fb0",O_RDWR)
> ioctl(fd, FBIOBLANK, ...)
>
> as i just use x+wm (no desktop environment) i wouldn't gain that much
> (but yes, it would be nicer anyway)
>
>> It would be better to use the pwm backlight devicetree binding though,
>> that way we can actually control brightness, and the upstream kernel
>> recently has gotten support for the pwm pins on the Axx SOCs.
>>
>> I would certainly welcome patches adding pwm backlight devicetree nodes
>> to supported devices, since we will need those in the future anyways.
>
> Brightness control would be nice. But I will have to learn how this is
> supposed to work, first.I have 2 untested branches with pwm backlight for the 2 tablets I have: https://github.com/wens/linux/tree/sun5i-hsg-h702-pwm-backlight https://github.com/wens/linux/tree/sun8i-pwm-backlight The DT bits are complete, as support for the AXPs is missing. (regulators for AXP221/223, GPIOs for AXP209) This should give you a sample to work on. ChenYu >> Note that a pwm backlight devicetree node will give you both a brightness >> and a bl_enable attribute, since not all desktop environments will do the >> right thing, we could als patch the fbdev and/or turbfo fb drivers to >> look for a backlight device in sysfs and toggle its bl_enable setting >> when dpms is turned on/off, I believe that that would be the best way >> to fix this until we get a kms driver. > > ok, will head into the pwm backlight direction. > thank you very much, again! > > greetings, jens > > -- > You received this message because you are subscribed to the Google Groups > "linux-sunxi" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to linux-sunxi+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
