On Wed, Mar 19, 2025 at 12:58:36AM +0100, Christian Marangi wrote: > A PCS provider have to implement and call of_pcs_add_provider() in > probe function and define an xlate function to define how the PCS > should be provided based on the requested interface and phandle spec > defined in DT (based on the #pcs-cells) > > of_pcs_get() is provided to provide a specific PCS declared in DT > an index. > > A simple xlate function is provided for simple single PCS > implementation, of_pcs_simple_get. > > A PCS provider on driver removal should first call > phylink_pcs_release() to release the PCS from phylink and then > delete itself as a provider with of_pcs_del_provider() helper. This is inherently racy. phylink_pcs_release() may release the PCS from phylink, but there is a window between calling this and of_pcs_del_provider() where it could still be "got". The sequence always has to be: First, unpublish to prevent new uses. Then remove from current uses. Then disable hardware/remove resources. It makes me exceedingly sad that we make keep implementing the same mistakes time and time again - it was brought up at one of the OLS conferences back in the 2000s, probably around the time that the driver model was just becoming "a thing". At least I can pass on this knowledge when I spot it and help others to improve! Note that networking's unregister_netdev() recognises this pattern, and unregister_netdev() will first unpublish the interface thereby making it inaccessible to be brought up, then take the interface down if it were up before returning - thus guaranteeing that when the function returns, it is safe to dispose of any and all resources that the driver was using. Sorry as I seem to be labouring this point. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
