On 10/23/2013 06:36 PM, Mark Zhang wrote: > On 10/23/2013 05:09 PM, Thierry Reding wrote: >> On Wed, Oct 23, 2013 at 04:49:29PM +0800, Mark Zhang wrote: >>> On 10/23/2013 04:00 PM, Thierry Reding wrote: >>>> On Wed, Oct 23, 2013 at 10:16:24AM +0800, Mark Zhang wrote: >>>>> On 10/22/2013 08:49 PM, Thierry Reding wrote: >>>>>> On Tue, Oct 22, 2013 at 04:55:09PM +0800, Mark Zhang wrote: >>>>>>> On 10/22/2013 03:24 PM, Thierry Reding wrote: >>>>>>>> On Fri, Oct 18, 2013 at 12:48:12PM +0800, Mark Zhang wrote: >>>>>>> [...] >>>>>>>>>> >>>>>>>>> >>>>>>>>> Okay, I just want to set the "notify" function pointer in "struct >>>>>>>>> platform_pwm_backlight_data", because I want to tune the brightness >>>>>>>>> value before the pwm-bl sets the brightness to hardware. I don't know >>>>>>>>> how to do that, unless we define the platform data explicitly. >>>>>>>> >>>>>>>> Okay, my question should have been what you need the functions for and >>>>>>>> why you think you need them. >>>>>>>> >>>>>>> >>>>>>> If I understanding you correctly, I suppose I've said that: "because I >>>>>>> want to tune the brightness value before the pwm-bl sets the brightness >>>>>>> to hardware". >>>>>> >>>>>> Why do you want to tune the brightness value? What are you trying to >>>>>> achieve? >>>>>> >>>>> >>>>> Oh, Tegra has a feature named PRISM(aka SmartDimmer). It changes the >>>>> color value to make the display looks bright so that we can reduce the >>>>> backlight brightness to save power. So everytime PRISM is triggered, we >>>>> call "backlight_update_status", then in the "notify" callback, we change >>>>> the brightness value which pwm-bl provides by considering the PRISM >>>>> compensations. >>>> >>>> If you automatically call backlight_update_status() everytime PRISM >>>> gives you new data, can't you just pass the correct value in in the >>>> first place so that you don't have to tweak it in the .notify() >>>> callback? >>> >>> OK, how to do that? -- "pass the correct value in in the first place"? >> >> Well, if you call backlight_update_status(), then you can pass in a >> brightness value, right? You usually do that by setting the backlight's >> props.brightness field. >> >> So when PRISM gives you new data, you could just read out the current >> brightness, compute the new one based on the current one and the PRISM >> data, set the props.brightness field to that value and then call >> backlight_update_status(). >> > > Okay, anyway, I got the idea. Actually it's simpler. :) > I'm just curious that if we can do that in this way, why we need > "notify" anymore? Oh, by the way, how about "check_fb" fops? Is there some kind of substitution as well? I mean, if I wanna set "check_fb" and also want to define the backlight device via DT, is there a way to do that? Mark > > Mark >> Thierry >> -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
