Hi Frieder On Mon, 10 Jul 2023 at 08:46, Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> wrote: > > On 07.07.23 21:00, Vladimir Lypak wrote: > > [Sie erhalten nicht häufig E-Mails von vladimir.lypak@xxxxxxxxx. Weitere Informationen, warum dies wichtig ist, finden Sie unter https://aka.ms/LearnAboutSenderIdentification ] > > > > In function drm_atomic_bridge_chain_post_disable handling of > > pre_enable_prev_first flag is broken because "next" variable will always > > end up set to value of "bridge". This breaks loop which should disable > > bridges in reverse: > > > > next = list_next_entry(bridge, chain_node); > > > > if (next->pre_enable_prev_first) { > > /* next bridge had requested that prev > > * was enabled first, so disabled last > > */ > > limit = next; > > > > /* Find the next bridge that has NOT requested > > * prev to be enabled first / disabled last > > */ > > list_for_each_entry_from(next, &encoder->bridge_chain, > > chain_node) { > > // Next condition is always true. It is likely meant to be inversed > > // according to comment above. But doing this uncovers another problem: > > // it won't work if there are few bridges with this flag set at the end. > > if (next->pre_enable_prev_first) { > > next = list_prev_entry(next, chain_node); > > limit = next; > > // Here we always set next = limit = branch at first iteration. > > break; > > } > > } > > > > /* Call these bridges in reverse order */ > > list_for_each_entry_from_reverse(next, &encoder->bridge_chain, > > chain_node) { > > // This loop never executes past this branch. > > if (next == bridge) > > break; > > > > drm_atomic_bridge_call_post_disable(next, old_state); > > > > In this patch logic for handling the flag is simplified. Temporary > > "iter" variable is introduced instead of "next" which is used only > > inside inner loops. > > > > Fixes: 4fb912e5e190 ("drm/bridge: Introduce pre_enable_prev_first to alter bridge init order") > > Signed-off-by: Vladimir Lypak <vladimir.lypak@xxxxxxxxx> > > I haven't had a chance to look at this, but I still want to reference > another patch by Jagan that intends to fix some bug in this area: > > https://patchwork.kernel.org/project/dri-devel/patch/20230328170752.1102347-1-jagan@xxxxxxxxxxxxxxxxxxxx/ > > +Cc: Jagan > > Dave, as you introduced this feature, did you have a chance to look at > Jagan's and Vladimir's patches? Sorry, they'd fallen off my radar. I'm having a look at the moment, but will probably need to carry it over to Monday. Dave
