On Thu, Jan 09, 2025 at 11:52:56PM +0800, Nick Chan wrote: > > Daniel Thompson 於 2025/1/8 下晝6:52 寫道: > > On Wed, Dec 11, 2024 at 07:34:38PM +0800, Nick Chan wrote: > >> Add driver for backlight controllers attached via Apple DWI 2-wire > >> interface, which is found on some Apple iPhones, iPads and iPod touches > >> with a LCD display. > >> > >> Although there is an existing apple_bl driver, it is for backlight > >> controllers on Intel Macs attached via PCI, which is completely different > >> from the Samsung-derived DWI block. > >> > >> Signed-off-by: Nick Chan <towinchenmi@xxxxxxxxx> > >> --- > >> drivers/video/backlight/Kconfig | 12 +++ > >> drivers/video/backlight/Makefile | 1 + > >> drivers/video/backlight/dwi_bl.c | 122 +++++++++++++++++++++++++++++++ > > I'd rather this was called apple_dwi_bl.c to match that config options, > > etc. > Still trying to determine the type of the backlight control, I think > it is linear however and I will send a new version when I am more > certain. If you've got an physicalinstance of the backlight then you can get a general idea by comparing levels: 512, 1024, 1536 and 2047. A linear backlight will feel make the gaps feel uneven (e.g. the difference between 1536 and 2047 will look very different to the difference difference between 512 and 1024). A logarithmic backligt will make the perceived brightness intervals between the above all feel pretty similar. Daniel.
