From: John Ogness <john.ogness@linutronix.de>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-riscv <linux-riscv@lists.infradead.org>
Subject: Re: [PATCH printk v5 1/1] printk: extend console_lock for per-console locking
Date: Thu, 23 Jun 2022 00:43:15 +0206 [thread overview]
Message-ID: <87v8ssgw9w.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <CAMuHMdWjzH6GGkaZ_5cjeC6stc80u9Ly+5rrBuk8rKMvM7==8w@mail.gmail.com>
On 2022-06-22, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> I have bisected another intriguing issue to this commit: on SiPEED
> MAiX BiT (Canaan K210 riscv), it no longer prints the line detecting
> ttySIF0, i.e. the console output changes like:
>
> spi-nor spi1.0: gd25lq128d (16384 Kbytes)
> i2c_dev: i2c /dev entries driver
> k210-fpioa 502b0000.pinmux: K210 FPIOA pin controller
> -38000000.serial: ttySIF0 at MMIO 0x38000000 (irq = 1, base_baud =
> 115200) is a SiFive UART v0
> printk: console [ttySIF0] enabled
> printk: bootconsole [sifive0] disabled
> printk: console [ttySIF0] printing thread started
>
> As this patch does not make any changes to drivers/tty/, and ttySIF0
> does work (it's the console), I looked in /proc/kmsg, and bingo,
> the missing line is there, so it is generated, but never printed.
What is sifive0? Are you using the earlycon driver to create an early
boot console? Can I see your boot args?
There is a known issue the that earlycon does not synchronize with
normal consoles. A patch was recently posted [0] on LKML.
> I tried taking the port spinlock in sifive_serial_startup(), as
> suggested for the meson driver, but that doesn't make a difference.
It may not have made a difference for you, but it should be there.
sifive_serial_startup() is writing to SIFIVE_SERIAL_IE_OFFS without
taking port->lock. sifive_serial_console_write() also writes to this
register (under port->lock). This could lead to RX watermark interrupts
being disabled for some time. The problem is not as bad as it was with
the meson driver because __ssp_enable_rxwm() is updating the shadow
copy. But still, it is a bug. And anyway we shouldn't have 2 CPUs
writing to a register simultaneously.
John Ogness
[0] https://lore.kernel.org/lkml/20220621090900.GB7891@pathway.suse.cz
WARNING: multiple messages have this Message-ID (diff)
From: John Ogness <john.ogness@linutronix.de>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-riscv <linux-riscv@lists.infradead.org>
Subject: Re: [PATCH printk v5 1/1] printk: extend console_lock for per-console locking
Date: Thu, 23 Jun 2022 00:43:15 +0206 [thread overview]
Message-ID: <87v8ssgw9w.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <CAMuHMdWjzH6GGkaZ_5cjeC6stc80u9Ly+5rrBuk8rKMvM7==8w@mail.gmail.com>
On 2022-06-22, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> I have bisected another intriguing issue to this commit: on SiPEED
> MAiX BiT (Canaan K210 riscv), it no longer prints the line detecting
> ttySIF0, i.e. the console output changes like:
>
> spi-nor spi1.0: gd25lq128d (16384 Kbytes)
> i2c_dev: i2c /dev entries driver
> k210-fpioa 502b0000.pinmux: K210 FPIOA pin controller
> -38000000.serial: ttySIF0 at MMIO 0x38000000 (irq = 1, base_baud =
> 115200) is a SiFive UART v0
> printk: console [ttySIF0] enabled
> printk: bootconsole [sifive0] disabled
> printk: console [ttySIF0] printing thread started
>
> As this patch does not make any changes to drivers/tty/, and ttySIF0
> does work (it's the console), I looked in /proc/kmsg, and bingo,
> the missing line is there, so it is generated, but never printed.
What is sifive0? Are you using the earlycon driver to create an early
boot console? Can I see your boot args?
There is a known issue the that earlycon does not synchronize with
normal consoles. A patch was recently posted [0] on LKML.
> I tried taking the port spinlock in sifive_serial_startup(), as
> suggested for the meson driver, but that doesn't make a difference.
It may not have made a difference for you, but it should be there.
sifive_serial_startup() is writing to SIFIVE_SERIAL_IE_OFFS without
taking port->lock. sifive_serial_console_write() also writes to this
register (under port->lock). This could lead to RX watermark interrupts
being disabled for some time. The problem is not as bad as it was with
the meson driver because __ssp_enable_rxwm() is updating the shadow
copy. But still, it is a bug. And anyway we shouldn't have 2 CPUs
writing to a register simultaneously.
John Ogness
[0] https://lore.kernel.org/lkml/20220621090900.GB7891@pathway.suse.cz
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next prev parent reply other threads:[~2022-06-22 22:37 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-21 21:22 [PATCH printk v4 00/15] implement threaded console printing John Ogness
2022-04-21 21:22 ` [PATCH printk v4 01/15] printk: rename cpulock functions John Ogness
2022-04-21 21:22 ` [PATCH printk v4 02/15] printk: cpu sync always disable interrupts John Ogness
2022-04-21 21:22 ` [PATCH printk v4 03/15] printk: add missing memory barrier to wake_up_klogd() John Ogness
2022-04-21 21:22 ` [PATCH printk v4 04/15] printk: wake up all waiters John Ogness
2022-04-21 21:22 ` [PATCH printk v4 05/15] printk: wake waiters for safe and NMI contexts John Ogness
2022-04-21 21:22 ` [PATCH printk v4 06/15] printk: get caller_id/timestamp after migration disable John Ogness
2022-04-21 21:22 ` [PATCH printk v4 07/15] printk: call boot_delay_msec() in printk_delay() John Ogness
2022-04-21 21:22 ` [PATCH printk v4 08/15] printk: add con_printk() macro for console details John Ogness
2022-04-21 21:22 ` [PATCH printk v4 09/15] printk: refactor and rework printing logic John Ogness
2022-04-21 21:22 ` [PATCH printk v4 10/15] printk: move buffer definitions into console_emit_next_record() caller John Ogness
2022-04-21 21:22 ` [PATCH printk v4 11/15] printk: add pr_flush() John Ogness
2022-04-21 21:22 ` [PATCH printk v4 12/15] printk: add functions to prefer direct printing John Ogness
2022-04-21 21:22 ` [PATCH printk v4 13/15] printk: add kthread console printers John Ogness
2022-04-22 7:48 ` Petr Mladek
2022-04-21 21:22 ` [PATCH printk v4 14/15] printk: extend console_lock for proper kthread support John Ogness
2022-04-21 21:40 ` John Ogness
2022-04-22 9:21 ` Petr Mladek
2022-04-25 20:58 ` [PATCH printk v5 1/1] printk: extend console_lock for per-console locking John Ogness
2022-04-26 12:07 ` Petr Mladek
2022-04-26 13:16 ` Petr Mladek
[not found] ` <CGME20220427070833eucas1p27a32ce7c41c0da26f05bd52155f0031c@eucas1p2.samsung.com>
2022-04-27 7:08 ` Marek Szyprowski
2022-04-27 7:08 ` Marek Szyprowski
2022-04-27 7:38 ` Petr Mladek
2022-04-27 7:38 ` Petr Mladek
2022-04-27 11:44 ` Marek Szyprowski
2022-04-27 11:44 ` Marek Szyprowski
2022-04-27 16:15 ` John Ogness
2022-04-27 16:15 ` John Ogness
2022-04-27 16:48 ` Petr Mladek
2022-04-27 16:48 ` Petr Mladek
2022-04-28 14:54 ` Petr Mladek
2022-04-28 14:54 ` Petr Mladek
2022-04-29 13:53 ` Marek Szyprowski
2022-04-29 13:53 ` Marek Szyprowski
2022-04-30 16:00 ` John Ogness
2022-04-30 16:00 ` John Ogness
2022-05-02 9:19 ` Marek Szyprowski
2022-05-02 9:19 ` Marek Szyprowski
2022-05-02 13:11 ` John Ogness
2022-05-02 13:11 ` John Ogness
2022-05-02 22:29 ` Marek Szyprowski
2022-05-02 22:29 ` Marek Szyprowski
2022-05-04 5:56 ` John Ogness
2022-05-04 5:56 ` John Ogness
2022-05-04 6:52 ` Marek Szyprowski
2022-05-04 6:52 ` Marek Szyprowski
2022-06-08 15:10 ` Geert Uytterhoeven
2022-06-08 15:10 ` Geert Uytterhoeven
2022-06-09 11:19 ` John Ogness
2022-06-09 11:19 ` John Ogness
2022-06-09 11:58 ` Jason A. Donenfeld
2022-06-09 11:58 ` Jason A. Donenfeld
2022-06-09 12:18 ` Dmitry Vyukov
2022-06-09 12:18 ` Dmitry Vyukov
2022-06-09 12:27 ` Jason A. Donenfeld
2022-06-09 12:27 ` Jason A. Donenfeld
2022-06-09 12:32 ` Dmitry Vyukov
2022-06-09 12:32 ` Dmitry Vyukov
2022-06-17 16:51 ` Sebastian Andrzej Siewior
2022-06-17 16:51 ` Sebastian Andrzej Siewior
2022-06-09 12:18 ` Jason A. Donenfeld
2022-06-09 12:18 ` Jason A. Donenfeld
2022-05-02 13:17 ` Petr Mladek
2022-05-02 13:17 ` Petr Mladek
2022-05-02 23:13 ` Marek Szyprowski
2022-05-02 23:13 ` Marek Szyprowski
2022-05-03 6:49 ` Petr Mladek
2022-05-03 6:49 ` Petr Mladek
2022-05-04 6:05 ` Marek Szyprowski
2022-05-04 6:05 ` Marek Szyprowski
2022-05-04 21:11 ` John Ogness
2022-05-04 21:11 ` John Ogness
2022-05-04 22:42 ` John Ogness
2022-05-04 22:42 ` John Ogness
2022-05-05 22:33 ` John Ogness
2022-05-05 22:33 ` John Ogness
2022-05-06 6:43 ` Marek Szyprowski
2022-05-06 6:43 ` Marek Szyprowski
2022-05-06 7:55 ` Neil Armstrong
2022-05-06 7:55 ` Neil Armstrong
2022-05-08 11:02 ` John Ogness
2022-05-08 11:02 ` John Ogness
2022-05-06 8:16 ` Petr Mladek
2022-05-06 8:16 ` Petr Mladek
2022-05-06 9:20 ` John Ogness
2022-05-06 9:20 ` John Ogness
[not found] ` <CGME20220506112526eucas1p2a3688f87d3ed8331b99f2f876bf6c2f6@eucas1p2.samsung.com>
2022-05-06 11:25 ` Marek Szyprowski
2022-05-06 12:41 ` John Ogness
2022-05-06 13:04 ` Marek Szyprowski
2022-06-22 9:03 ` Geert Uytterhoeven
2022-06-22 9:03 ` Geert Uytterhoeven
2022-06-22 22:37 ` John Ogness [this message]
2022-06-22 22:37 ` John Ogness
2022-06-23 10:10 ` Geert Uytterhoeven
2022-06-23 10:10 ` Geert Uytterhoeven
2022-04-21 21:22 ` [PATCH printk v4 15/15] printk: remove @console_locked John Ogness
2022-04-22 9:39 ` [PATCH printk v4 00/15] implement threaded console printing Petr Mladek
2022-04-22 20:29 ` Petr Mladek
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