On Tue, 19 Aug, 2025 11:06:40 +0200 "Maxime Ripard" <[email protected]> wrote: > Hi Rahul, > > On Mon, Aug 18, 2025 at 05:04:15AM +0000, Rahul Rameshbabu wrote: >> I am working on a drm_connector scoped backlight API in Rust. I have been >> looking through Hans de Goede's previous efforts on this topic to help >> guide my design. My hope is to enable backlight control over external >> displays through DDC or USB Monitor Control Class while also supporting >> internal panels. In parallel, I would like to improve the driver >> probing/selection mechanism when there are different candidates for driving >> a backlight device. This initial RFC is mainly intended to sanity check >> that the plumbing I have chosen for extending the DRM connector >> functionality in Rust seems reasonable. > > It's a great goal, and I had that same discussion with Hans recently > too, but I can't find the link between backling/DDC CI, and Rust. Can > you elaborate?
Hi Maxime, Sure, let me elaborate on this. You are right that plumbing DDC CI/backlight support at the DRM connector level does not need to be implemented in Rust. If we look at Hans's proposal, the suggested phase 2 was to add a drm_connector helper function for plumbing a pointer to the backlight device implementation. I had some model differences with regards to how the API would look like, mostly stemming from concerns about providing better runtime overriding of the acpi_video_get_backlight_type based backlight selection. However, I am aligned with the direction of scoping at the drm_connector level. I basically was interested in implementing this helper functionality in Rust instead of C, which is where Rust came into play. I was also interested in declaring and attaching a drm_property in Rust for controlling properties such as backlight rather than updating the drm_connector declaration in C as an experiment. Let me know if you feel like this work would be better off as a C implementation. I can also send out a detailed architecture proposal to the mailing list if that would help. Link: https://lore.freedesktop.org/wayland-devel/[email protected]/ Thanks, Rahul Rameshbabu > > Maxime
