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?
