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

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Thu, Aug 04, 2022 at 01:39:44PM +0530, Sanjay R Mehta wrote:
> 
> 
> 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.

How about splitting this into tb_discover_dp_resources() that then calls
tb_discover_dp_resource() for a single router? Whatever is the simplest ;-)