Messages in this thread | | | Date | Wed, 23 May 2018 10:58:59 -0700 | From | Tony Lindgren <> | Subject | Re: [PATCH v1 0/3] console, serial8250: Disable PM and DMA ops |
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* Andy Shevchenko <andy.shevchenko@gmail.com> [180522 21:42]: > On Thu, May 17, 2018 at 10:30 PM, Tony Lindgren <tony@atomide.com> wrote: > > So how about add some "noidle" kernel command line parameter for console > > that calls > > pm_runtime_forbid() and then you have the UART permanently > > on. > > IIUC _forbid() can be overwritten via sysfs. > And I would prefer to do other way around, something like console.idle > and put default for OMAP to yes and no for everything else.
OK yeah console.idle sounds good to me. We should default to a safe option.
> > Hmm I guess you could make also serial8250_rpm_get() do nothing > > based on that. > > Have you seen entire series which I keep here: > https://bitbucket.org/andy-shev/linux/branch/topic/uart/rpm? > Among other things it gets rid of those specific callbacks entirely.
Well I was not Cc:ed on it, I browsed it in some archive and it seemed unsafe to me. But if you figured out a way to do it conditionally based on console.idle without causing regressions.
> > I do agree the serial runtime PM has an issue if it depends on > > pm_runtime_irq_safe() being set. > > It's more than an issue. The so called "support" of RPM for UART is > _based on the hack_. > I would love to NAK that in the first place if I would have known of it in time.
Hmm well it seems that you too have been patching the 8250_rpm functions for years and then now what after multiple years you hit this issue? :)
> >> So, I can, of course just remove callbacks from the console ->write(). > >> Though it will prevent to use kernel console anyway. > > > > Please et's not start breaking things, we already see a constant > > flow of regressions on weekly basis. > > Now we are stick with a hack and the case based on that is against > fixing things. > This is how it looks from my side.
Sorry yeah I agree there are issues, but let's fix it properly with no regressions.
Regards,
TOny
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