Re: [PATCH v8 1/9] dt-bindings: display: fsl,ldb: Add i.MX94 LDB

On 3/20/26 9:23 AM, Marco Felsch wrote:

Hello Marco,

quoted

The LDB driver was always written with parsing 'reg' out of the DT, so

Not sure what you mean by always.

By always, I mean since the very beginning.

I re-checked the imx6qdl.dtsi which
uses the ipuv3/imx-ldb.c driver. These platforms don't use the 'reg'
property either.

Which is a different driver, although for a similar IP. We are however 
currently talking about drivers/gpu/drm/bridge/fsl-ldb.c , right ?

quoted

encoding the register offsets into the driver was a mistake. The LDB
controls two registers, which can be comfortably described in DT.

Sorry but I have to disagree on this. It's no about if it's possible,
it's about if the abstraction is correct and IMHO the LDB is just one
subdevice of the syscon. For i.MX6SX the syscon is the iomuxc-gpr for
the i.MX8M and i.MX9 this is now a blkctrl.

Right, and the "reg" DT property specifies at which offsets are the LDB 
control registers from the start of that blkctrl. What is the problem 
with that ?

Look at e.g. imx8mp.dtsi as an example with blkctrl and LDB as a subnode 
with "reg" DT properties:

1938                         media_blk_ctrl: blk-ctrl@32ec0000 {
1939                                 compatible = 
"fsl,imx8mp-media-blk-ctrl",
1940                                              "syscon";
...
2003                                 lvds_bridge: bridge@5c {
2004                                         compatible = "fsl,imx8mp-ldb";
2005                                         reg = <0x5c 0x4>, <0x128 0x4>;
2006                                         reg-names = "ldb", "lvds";