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From: Andy Shevchenko <firstname.lastname@example.org>
To: Tony Lindgren <email@example.com>,
Andy Shevchenko <firstname.lastname@example.org>
Cc: Sebastian Andrzej Siewior <email@example.com>,
Petr Mladek <firstname.lastname@example.org>,
Sergey Senozhatsky <email@example.com>,
Steven Rostedt <firstname.lastname@example.org>,
Linux Kernel Mailing List <email@example.com>,
Greg Kroah-Hartman <firstname.lastname@example.org>,
Jiri Slaby <email@example.com>,
"open list:SERIAL DRIVERS" <firstname.lastname@example.org>,
Arnd Bergmann <email@example.com>
Subject: Re: [PATCH v1 0/3] console, serial8250: Disable PM and DMA ops
Date: Wed, 18 Jul 2018 18:14:03 +0300 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
On Wed, 2018-05-23 at 10:58 -0700, Tony Lindgren wrote:
> * Andy Shevchenko <email@example.com> [180522 21:42]:
> > On Thu, May 17, 2018 at 10:30 PM, Tony Lindgren <firstname.lastname@example.org>
> > 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
> 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
> 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 <email@example.com>
Intel Finland Oy
next prev parent reply other threads:[~2018-07-18 15:14 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-15 18:34 Andy Shevchenko
2018-05-15 18:34 ` [PATCH v1 1/3] console: introduce ->exit() callback Andy Shevchenko
2018-05-15 18:34 ` [PATCH v1 2/3] serial: 8250_port: Don't use power management for kernel console Andy Shevchenko
2018-05-15 18:34 ` [PATCH v1 3/3] serial: 8250_port: Disable DMA operations " Andy Shevchenko
2018-05-16 10:55 ` Sebastian Andrzej Siewior
2018-05-16 12:58 ` Andy Shevchenko
2018-05-16 18:20 ` Sebastian Andrzej Siewior
2018-05-15 18:37 ` [PATCH v1 0/3] console, serial8250: Disable PM and DMA ops Andy Shevchenko
2018-05-16 10:08 ` Sebastian Andrzej Siewior
2018-05-16 10:17 ` Andy Shevchenko
2018-05-16 10:47 ` Sebastian Andrzej Siewior
2018-05-16 13:10 ` Andy Shevchenko
2018-05-17 13:56 ` Tony Lindgren
2018-05-17 16:38 ` Andy Shevchenko
2018-05-17 19:30 ` Tony Lindgren
2018-05-22 21:39 ` Andy Shevchenko
2018-05-23 17:58 ` Tony Lindgren
2018-05-23 18:32 ` Tony Lindgren
2018-07-18 15:14 ` Andy Shevchenko [this message]
2018-07-19 6:47 ` Tony Lindgren
2018-05-17 17:04 ` Tony Lindgren
2018-05-17 13:48 ` Tony Lindgren
2018-05-17 16:36 ` Andy Shevchenko
2018-05-17 19:48 ` Tony Lindgren
2018-05-22 21:52 ` Andy Shevchenko
2018-05-23 18:00 ` Tony Lindgren
2018-07-18 14:50 ` Andy Shevchenko
2018-07-19 6:50 ` Tony Lindgren
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