Re: [RFC PATCH 1/6] drm/dp: Helpers to make it easier for drivers to use DP AUX bus properly

[Doug Anderson]

Hi,

On Mon, Apr 18, 2022 at 4:10 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
>
> So I guess where does that leave us? Maybe:
>
> 1. I'll add a WARN_ON() in of_dp_aux_populate_ep_devices() if there is
> more than one DP AUX endpoint with a comment explaining why we assume
> one DP AUX endpoint.
>
> 2. I'll create this new structure in drm_dp_aux_bus.h:
>
> struct dp_aux_populate_callbacks {
>   int (*done_probing)(struct drm_dp_aux *aux);
>   void (*pre_remove)(struct drm_dp_aux *aux);
> };
>
> 3. I'll add a second version of the populate functions that AUX bus
> providers can use if they want callbacks:
>
> int of_dp_aux_populate_ep_devices_cb(struct drm_dp_aux *aux,
>                                      struct dp_aux_populate_callbacks *cb);
> int devm_of_dp_aux_populate_ep_devices_cb(struct drm_dp_aux *aux,
>                                           struct dp_aux_populate_callbacks *cb);
>
> The old functions will just be changed to wrap the above and pass NULL
> for the callbacks. To me, this seems better/simpler than notifiers or
> any other scheme, but yell if you disagree.
>
> 4. I'll call the callsbacks in dp_aux_ep_probe() after a successful
> probe. I'll add a second callback and will call it in
> dp_aux_ep_remove() before passing the remove through to the panel.
>
>
> If that sounds peachy then I think it should be pretty doable.

I never heard any response about whether people liked the above, but I
went ahead and did something similar to it. It can be found at:

https://lore.kernel.org/r/20220503224029.3195306-1-dianders@xxxxxxxxxxxx