Messages in this thread | | | Date | Thu, 28 Mar 2013 19:06:45 +0100 | From | Richard GENOUD <> | Subject | Re: [PATCH 4/4] pinctrl: re-enable old state in case of error in pinctrl_select_state |
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On [jeu., 28.03.2013 11:38:23], Stephen Warren wrote: > On 03/28/2013 11:34 AM, Richard GENOUD wrote: > > On [mer., 27.03.2013 17:55:45], Stephen Warren wrote: > >> On 03/25/2013 08:47 AM, Richard Genoud wrote: > >>> If a new state is applied, the groups configured in the old state but > >>> not in the new state are disabled. > >>> If something goes wrong and the new state can't be applied, we have to > >>> re-enable those groups. > >> > >> What is the use-case for this? I wonder if it isn't better to simply > >> undo the partial selection of the new state (as patch 3/4 attempts to > >> do) and then leave p->state==NULL, indicating that no state is actively > >> selected. IIRC, this would be the same as right after the initial > >> pinctrl_select(). > >> > >> I wonder if it's likely that attempting to re-apply the old state would > >> actually work, given that applying something just failed. > >> > >> Finally, this recovery code doesn't: > >> > >> a) Process anything except MUX_GROUP; any pin config settings in the old > >> state aren't restored. > >> > >> b) (I think) Apply any mux settings that don't involve groups that are > >> referenced by both the old and new states; given that patch 3/4 attempts > >> to undo everything in the failed application of the new state, I think > >> this "re-apply the old state" code should simple run through everything > >> in the old state any apply it unconditionally. > > > > So, if I understand correctly, it could be as simple as that: > > } > > > > - if (old_state) { > > - list_for_each_entry(setting, &old_state->settings, node) { > > - bool found = false; > > - if (setting->type != PIN_MAP_TYPE_MUX_GROUP) > > - continue; > > - list_for_each_entry(setting2, &state->settings, node) { > > - if (setting2->type != PIN_MAP_TYPE_MUX_GROUP) > > - continue; > > - if (setting2->data.mux.group == > > - setting->data.mux.group) { > > - found = true; > > - break; > > - } > > - } > > - if (!found) > > - pinmux_enable_setting(setting); > > - } > > - } > > - > > p->state = old_state; > > I think you want to remove that line too, so that p->state == NULL in > the error case, so that if the pinctrl_select_state_locked() call below > also fails to restore the old state, then (!old_state) will be true > inside the recursive call, so it doesn't recurse into itself forever. > > > + if (old_state) > > + pinctrl_select_state_locked(p, NULL); > > You want to pass old_state rather than NULL there, I think. Hum, I'm starting to code nonsense. It's time to go home !
But yes, we clearly don't want to have p->state != NULL in the recursive call (I've seen that, and an evil force made me wrote the contrary :))
So, just: + if (old_state) + pinctrl_select_state_locked(p, old_state); Will do the trick. It can't loop forever as p->state is null. If it fails, p->state will be still null. If it succeeds, p->state will be == old_state, and that's what we want.
Got it !(finally)
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