I can confirm that I also need video.use_native_backlight=1 plus this patch (applied to 3.12-rc5) in order to make things work on my T430s laptop:
Handle 0x000F, DMI type 1, 27 bytes System Information Manufacturer: LENOVO Product Name: 2352CTO Version: ThinkPad T430s Wake-up Type: Power Switch SKU Number: LENOVO_MT_2352 Family: ThinkPad T430s
I can confirm that I also need video.use_ native_ backlight= 1 plus this patch (applied to 3.12-rc5) in order to make things work on my T430s laptop:
Handle 0x000F, DMI type 1, 27 bytes
Manufacturer: LENOVO
System Information
Product Name: 2352CTO
Version: ThinkPad T430s
Wake-up Type: Power Switch
SKU Number: LENOVO_MT_2352
Family: ThinkPad T430s