Your framing here is astoundingly biased and doesn't reflect what most reasonable people have understood to be the case. (That the vast majority of the violence comes from police.)
The protests aren't peaceful, but that's deliberate. "No Justice; No Peace" means something. The protesters have been non-violent, but non-peaceful on purpose. The police have consistently escalated (just like they did in Seattle.)
Here is what I can't figure out. What would have to happen in Portland for the protestors to stop protesting? What would represent success? I honestly don't know. Am I wrong to think that most residents of Portland would like their community to go back to some sort of "normal" peaceful routine? How can that happen if there is a minority of residents who have a perpetual veto on returning to "normal"? And even if the demonstrations stopped and therefore the police reaction to demonstrations stopped, doesn't "normal" policing have to happen? What type of policing would be accepted by those who are protesting?
* Defunding. There was a moderate budget cut already, but we want more, and we want the city to not just remove budget from PPB but actually put money into social welfare programs.
* Non-violence. The city council and mayor theoretically have the power to order the police to stop using tear gas right now, and similarly they could order the police to be less violent in all of their activities.
* Justice. The police are failing to arrest fascist street thugs, and instead send them text messages letting them know not to show up [0]. Meanwhile they do nothing to prevent federal officers from using unmarked vans to yank people off the streets.
* Polis. The police mostly live in Vancouver or its suburbs, over in Washington State. This is absurd; police ought to live in their respective precincts, just like how city councillors must live in their district. Even my credit union requires me to live in my county!
* Reform. There are many popular initiatives [1] which would force police work to be more humane and considerate, if only they were adopted.
I would consider any of those to be a victory. We got some defunding earlier, and protestors agreed that it was a good token effort but not enough.
Nobody wants the old routine of police violence and abuse. Nobody particularly wants to be tear-gassed, I think.
I am too far away from the details and the history of the Portland police department to pretend to know what the right course of action is, but it seems to me that the "non-peaceful" part of the protest is actually making any resolution that much more difficult. That is to say it is a tactic that makes the problem worse not better.
I'm also pretty mystified as to why the normal political process was not able to resolve concerns about police activities/methodologies. As far as I can tell from afar, all the Portland elected officials are ideologically aligned with those initiatives. What prevented them from responding and if there really isn't the political will to make those changes through normal peaceful means, by what right to the protesters get to force their will on the entire community?
This is a tough question. When minorities are being targeted, don't have sufficient access to resources, can't engage in political processes, etc, how do they advocate for themselves? The routes you suggest are great, but aren't available to everyone or have been set up to specifically exclude people.
I feel like that it is necessary to be more specific in order to justify using force and abandoning the system. In Portland, who is targeting minorities? What does "targeting" mean? If the elected officials are sympathetic to those problems (what ever the details), what prevents them from addressing those problems? What resources are required to "participate" that aren't available? In a small city doesn't that just mean going to meetings? voting? etc. How are people being "excluded"? Is there a problem with the DAs office that they aren't prosecuting the unlawful actions against minorities?
If there is really a story about elected officials ignoring or contributing to violations of individual rights, failure to ensure due process, failure to manage the police force, and so on then why isn't that story being told or reported on? If that is really the back story then the protestors have utterly failed to communicate that in an environment where it should be almost trivial to gain public visibility for those problems.
Portland is even more puzzling because I believe the Mayor is also the police commissioner so there shouldn't be any problem with control of police policy as there can be in other jurisdictions where there is less direct oversight of the police.
The protests aren't peaceful, but that's deliberate. "No Justice; No Peace" means something. The protesters have been non-violent, but non-peaceful on purpose. The police have consistently escalated (just like they did in Seattle.)