On Wed, 2018-05-23 at 10:58 -0700, Tony Lindgren wrote: > * Andy Shevchenko <andy.shevchenko@xxxxxxxxx> [180522 21:42]: > > On Thu, May 17, 2018 at 10:30 PM, Tony Lindgren <tony@xxxxxxxxxxx> > > 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. I'll see what we can do here. > > > 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 restored that branch with some updated patches. It's far from done and doesn't have any new stuff (yet) regrading to this discussion. > > > 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? :) Nope, I hit it as soon as I tried. I can't find easily the discussion (hmm... yes, I was so pissed off that time, I put a bit of harsh in that) I had with Sebastian few years back, but at least I reported about an 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 Agree. > with > no regressions. ...though I think a word "regression" is inappropriate here. Regression is what the support did in the first place. Pity I didn't know about it at that time. -- Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Intel Finland Oy -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
