On Mon, May 26, 2025 at 4:53 PM Jani Nikula <[email protected]> wrote: > On Sun, 25 May 2025, Pengyu Luo <[email protected]> wrote: > > When registering a backlight device, if a device with the same name > > already exists, append "-secondary" to the new device's name. This is > > useful for platforms with dual backlight drivers (e.g. some panels use > > dual ktz8866), where both instances need to coexist. > > > > For now, only one secondary instance is supported. If more instances > > are needed, this logic can be extended with auto-increment or a more > > flexible naming scheme. > > I think for both patches you should consider adding a new interface for > creating dual backlight scenarios. > > For example, this patch turns a driver error (registering two or more > backlights with the same name) into a special use case, patch 2 > magically connecting the two, and hiding the problem. > > With i915, you could have multiple devices, each with multiple > independent panels with independent backlights. I think accidentally > trying to register more than one backlight with the same name should > remain an error, *unless* you want the special case of combined > backlights. > > Similarly, what if you encounter a device with two panels, and two > *independent* ktz8866? > > Please be explicit rather than implicit. >
For i915, I noticed that it renamed the device internally, so I tried to rename it in the backlight driver. Indeed, patch 2 may combine independent panels, I was playing with android tablet, and I ignored it, you had well explained it. Thanks for pointing out, I will consider adding a new interface. Best wishes, Pengyu
