On Thu, May 20, 2021 at 6:54 AM Zhen Lei [off-list ref] wrote:

There is a variant driver of pl011, which may have a compatible string
written as: "arm,sbsa-uart", "arm,pl011". Because it contains "arm,pl011",
so the corresponding device tree nodes are also checked by this YAML file.
As a result, many flase warnings similar to the following are reported:

arch/arm64/boot/dts/freescale/fsl-lx2160a-clearfog-cx.dt.yaml:
 serial@21c0000: compatible:0: 'arm,pl011' was expected
 serial@21c0000: compatible:1: 'arm,primecell' was expected

The DT is wrong. The h/w is either a PL011 or it isn't. If it is, then
the compatible should be '"arm,pl011", "arm,primecell"'. There is no
point in making it 'arm,sbsa-uart' as the PL011 (and OS support for
it) predate SBSA (by a lot). If it is not a PL011 and only the SBSA
subset, then it should be "arm,sbsa-uart".

Rob