Bonjour, bienvenue a OpenWrt
frollic a raison, c'est un forum anglais.
The DGS-1210-08P is not supported. The DGS-1210 series is a large series of switches, I don't think the SoC that OpenWrt supports started to be used until the F1 revision of the -10P. There was some work to make custom builds for older switches, including the -08P. See here:
It looks like it will be some task to get OpenWrt to work on it.
It may be possible to support some of the A and B versions of the D-Link DGS-1210 series as the SOC used is a derived from the Marvell Kirkwood series. There is a dtsi file for one version of the switch SOC kirkwood-98dx4122.dtsi and two devices that make use of the dtsi (kirkwood-km_fixedeth.dts, kirkwood-km_kirkwood.dts) available in the mainline kernel. I have no idea how complete the support is, but this might be a good starting point for anyone inclined to attempt adding support for the Marvell based switches.