On 2024-11-05, Petr Mladek <pmladek@xxxxxxxx> wrote: > Observation: > > + CON_ENABLED is not needed for the original purpose. Only enabled > consoles are added into @console_list. > > + CON_ENABLED is still used to explicitely block the console driver > during suspend by console_stop()/console_start() in serial_core.c. > > It is not bad. But it is a bit confusing because we have > CON_SUSPENDED flag now and this is about suspend/resume. Also note that CON_ENABLED is used to gate ->unblank(). It should probably consider CON_SUSPENDED as well. > + CON_SUSPENDED is per-console flag but it is set synchronously > for all consoles. > > IMHO, a global variable would make more sense for the big hammer > purpose. > > > Big question: > > Does the driver really needs to call console_stop()/console_start() > when there is the big hammer? > > I would preserve it because it makes the design more robust. Agreed. They serve different purposes. console_stop()/console_start() is a method for _drivers_ to communicate that they must not be called because their hardware is not available/functioning. console_suspend()/console_resume() is a method for the _system_ to communicate that consoles should be silent because they are annoying or we do not trust that they won't cause problems. > Anyway, the driver-specific handling looks like the right solution. > The big hammer feels like a workaround. Agreed. Do the 6 call sites even really need the big hammer? I am guessing yes because there are probably console drivers that do not use console_stop()/console_start() in their suspend/resume and thus rely on the whole subsystem being disabled. > Reasonable semantic: > > 1. Rename: > > console_suspend() -> console_suspend_all() > console_resume() -> console_resume_all() > > and manipulate a global @consoles_suspended variable agagin. > It is the big hammer API. Agreed. As a global variable, it can still rely on SRCU for synchronization. > 2. Rename: > > console_stop(con) -> console_suspend(con) > console_start(con) -> console_resume(con) > > and manipulare the per-console CON_SUSPENDED flag here. Agreed. > 3. Get rid of the ambiguous CON_ENABLED flag. It won't longer > have any purpose. > > Except that it is also used to force console registration. > But it can be done a better way, e.g. by introducing > register_console_force() API. Agreed. John
