LKML Archive on lore.kernel.org help / color / mirror / Atom feed
From: Andy Shevchenko <firstname.lastname@example.org> To: Tony Lindgren <email@example.com> Cc: Andy Shevchenko <firstname.lastname@example.org>, 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, 23 May 2018 00:39:46 +0300 [thread overview] Message-ID: <CAHp75Ve56pyEC41XZ9i9yxBNberQe=ee2miQL0v9T4vRtkWPBQ@mail.gmail.com> (raw) In-Reply-To: <20180517193008.GV25808@atomide.com> On Thu, May 17, 2018 at 10:30 PM, Tony Lindgren <firstname.lastname@example.org> wrote: > * Andy Shevchenko <email@example.com> [180517 16:41]: >> On Thu, May 17, 2018 at 4:56 PM, Tony Lindgren <firstname.lastname@example.org> wrote: >> > * Andy Shevchenko <email@example.com> [180516 13:12]: >> >> On Wed, 2018-05-16 at 12:47 +0200, Sebastian Andrzej Siewior wrote: >> >> > But since I am on it. You have to enable runtime-PM for the UART. So >> >> > what is the problem if you simply don't enable it for the UART which >> >> > used as the kernel console? >> >> >> >> How do I know at the ->probe() time that device in question is going to >> >> be kernel console? Maybe I missed simple way of it. >> > >> > Hmm parse the kernel cmdline maybe? :) >> > >> > BTW, kernel already has earlycon doing exactly what you're trying to do. >> >> I'm sorry, I didn't follow. What exactly earlycon does? > > It provides a console very early on, see earlycon in > Documentation/admin-guide/kernel-parameters.txt Yes, but what we are talking is to put the kernel console out of power management due to _real_ issues with it. >> The problem is in 8250 driver. The issue with runtime PM used in atomic context. > > 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. > 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. > 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. >> 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. -- With Best Regards, Andy Shevchenko
next prev parent reply other threads:[~2018-05-22 21:39 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-15 18:34 [PATCH v1 0/3] console, serial8250: Disable PM and DMA ops 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 [this message] 2018-05-23 17:58 ` Tony Lindgren 2018-05-23 18:32 ` Tony Lindgren 2018-07-18 15:14 ` Andy Shevchenko 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
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to='CAHp75Ve56pyEC41XZ9i9yxBNberQe=ee2miQL0v9T4vRtkWPBQ@mail.gmail.com' \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).