Re: [PATCH v3] thunderbolt: Add DP out resource when DP tunnel is discovered.

[Sanjay R Mehta <sanmehta@amd.com>]

On 8/4/2022 12:38 PM, Mika Westerberg wrote:
> On Thu, Aug 04, 2022 at 12:34:09PM +0530, Sanjay R Mehta wrote:
>>>>  			tunnel = tb_tunnel_discover_dp(tb, port, alloc_hopids);
>>>
>>> Here tunnel can be NULL...
>>>
>>>> +			tb_dp_resource_available_discovered(tb, tunnel->dst_port);
>>>
>>> ... so this will crash and burn.
>>
>> Thanks. Agree, I will add check here and resend the patch.
> 
> Please don't add the check here but move this to tb_start() as I
> suggested.

Sure Mika.

As you earlier suggested to move this function to either "tb_start() or
tb_discover_tunnels()".


Since adding of this DP OUT resource is required for each DP tunnel,
hence I felt it will be better if I move this function in
tb_discover_tunnels() where we can avoid extra for loop for tunnel.

Below is the place how I am thinking of adding
"tb_discover_dp_resources()" function.


static void tb_discover_tunnels(struct tb *tb)
{
        struct tb_cm *tcm = tb_priv(tb);
        struct tb_tunnel *tunnel;

        tb_switch_discover_tunnels(tb->root_switch, &tcm->tunnel_list,
true);

        list_for_each_entry(tunnel, &tcm->tunnel_list, list) {
                if (tb_tunnel_is_pci(tunnel)) {
                        struct tb_switch *parent = tunnel->dst_port->sw;

                        while (parent != tunnel->src_port->sw) {
                                parent->boot = true;
                                parent = tb_switch_parent(parent);
                        }
                } else if (tb_tunnel_is_dp(tunnel)) {
                        /* Keep the domain from powering down */
                        tb_discover_dp_resources(tb, tunnel->dst_port);
                        pm_runtime_get_sync(&tunnel->src_port->sw->dev);
                        pm_runtime_get_sync(&tunnel->dst_port->sw->dev);
                }
        }
}


Does this make sense? Please suggest me if I have to do it other way.
Appreciate your help.