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From: Nicholas Piggin <npiggin@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, Jiri Slaby <jslaby@suse.com>,
	linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH 04/15] powerpc/powernv: opal-kmsg use flush fallback from console code
Date: Tue, 8 May 2018 13:40:13 +1000	[thread overview]
Message-ID: <20180508134013.472b7981@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <87wowfbvm0.fsf@concordia.ellerman.id.au>

On Mon, 07 May 2018 20:36:39 +1000
Michael Ellerman <mpe@ellerman.id.au> wrote:

> Nicholas Piggin <npiggin@gmail.com> writes:
> > On Fri, 04 May 2018 15:16:37 +1000
> > Michael Ellerman <mpe@ellerman.id.au> wrote:  
> >> Nicholas Piggin <npiggin@gmail.com> writes:  
> >> > Use the more refined and tested event polling loop from opal_put_chars
> >> > as the fallback console flush in the opal-kmsg path. This loop is used
> >> > by the console driver today, whereas the opal-kmsg fallback is not
> >> > likely to have been used for years.
> >> >
> >> > Use WARN_ONCE rather than a printk when the fallback is invoked to
> >> > prepare for moving the console flush into a common function.    
> >> 
> >> Do we want to add a WARN in that path? If we're panicking things might
> >> get worse if we WARN (which takes a trap).  
> >
> > True, probably a good idea not to... oh there's a printk_once so
> > that'll work nicely.  
> 
> Cool.
> 
> I have this series in a tree so you can send me an incremental diff if
> it's reasonably small.

It's a one liner (also moved location of message back to where it was
originally).

The next patch will clash because it moves this over into opal.c, so
you'd have to fix that by hand.

Thanks,
Nick

---
 arch/powerpc/platforms/powernv/opal-kmsg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c b/arch/powerpc/platforms/powernv/opal-kmsg.c
index fd2bbf4fd6dc..c610ef3541aa 100644
--- a/arch/powerpc/platforms/powernv/opal-kmsg.c
+++ b/arch/powerpc/platforms/powernv/opal-kmsg.c
@@ -53,12 +53,12 @@ static void force_opal_console_flush(struct kmsg_dumper *dumper,
 	} else {
 		__be64 evt;
 
-		WARN_ONCE(1, "opal: OPAL_CONSOLE_FLUSH missing.\n");
 		/*
 		 * If OPAL_CONSOLE_FLUSH is not implemented in the firmware,
 		 * the console can still be flushed by calling the polling
 		 * function while it has OPAL_EVENT_CONSOLE_OUTPUT events.
 		 */
+		printk_once(KERN_NOTICE "opal: OPAL_CONSOLE_FLUSH missing.\n");
 		do {
 			opal_poll_events(&evt);
 		} while (be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT);
-- 
2.17.0

  reply	other threads:[~2018-05-08  3:40 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30 14:55 [PATCH 00/15] hvc and powerpc opal console latency reduction Nicholas Piggin
2018-04-30 14:55 ` [PATCH 01/15] powerpc/powernv: opal_put_chars partial write fix Nicholas Piggin
2018-07-24 13:59   ` [01/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 02/15] powerpc/powernv: Fix OPAL console driver OPAL_BUSY loops Nicholas Piggin
2018-04-30 14:55 ` [PATCH 03/15] powerpc/powernv: opal-kmsg standardise OPAL_BUSY handling Nicholas Piggin
2018-04-30 14:55 ` [PATCH 04/15] powerpc/powernv: opal-kmsg use flush fallback from console code Nicholas Piggin
2018-05-04  5:16   ` Michael Ellerman
2018-05-04  5:37     ` Nicholas Piggin
2018-05-07 10:36       ` Michael Ellerman
2018-05-08  3:40         ` Nicholas Piggin [this message]
2018-04-30 14:55 ` [PATCH 05/15] powerpc/powernv: Implement and use opal_flush_console Nicholas Piggin
2018-04-30 14:55 ` [PATCH 06/15] powerpc/powernv: Remove OPALv1 support from opal console driver Nicholas Piggin
2018-04-30 14:55 ` [PATCH 07/15] powerpc/powernv: move opal console flushing to udbg Nicholas Piggin
2018-04-30 14:55 ` [PATCH 08/15] powerpc/powernv: implement opal_put_chars_atomic Nicholas Piggin
2018-05-01  9:48   ` Benjamin Herrenschmidt
2018-05-01 10:37     ` Nicholas Piggin
2018-05-07 10:35       ` Michael Ellerman
2018-05-08  3:36         ` Nicholas Piggin
2018-04-30 14:55 ` [PATCH 09/15] tty: hvc: remove unexplained "just in case" spin delay Nicholas Piggin
2018-04-30 14:55 ` [PATCH 10/15] tty: hvc: use mutex instead of spinlock for hvc_structs lock Nicholas Piggin
2018-08-13 11:22   ` [10/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 11/15] tty: hvc: hvc_poll break hv read loop Nicholas Piggin
2018-08-13 11:23   ` [11/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 12/15] tty: hvc: hvc_poll may sleep Nicholas Piggin
2018-08-13 11:23   ` [12/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 13/15] tty: hvc: hvc_write " Nicholas Piggin
2018-08-13 11:23   ` [13/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 14/15] tty: hvc: introduce the hv_ops.flush operation for hvc drivers Nicholas Piggin
2018-08-13 11:23   ` [14/15] " Michael Ellerman
2018-04-30 14:55 ` [PATCH 15/15] powerpc/powernv: provide a console flush operation for opal hvc driver Nicholas Piggin
2018-08-21 10:35   ` [15/15] " Michael Ellerman

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