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From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 04/15] powerpc/powernv: opal-kmsg use flush fallback from console code
Date: Tue,  1 May 2018 00:55:47 +1000	[thread overview]
Message-ID: <20180430145558.4308-5-npiggin@gmail.com> (raw)
In-Reply-To: <20180430145558.4308-1-npiggin@gmail.com>

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.

Reviewed-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/platforms/powernv/opal-kmsg.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c b/arch/powerpc/platforms/powernv/opal-kmsg.c
index f8f41ccce75f..fd2bbf4fd6dc 100644
--- a/arch/powerpc/platforms/powernv/opal-kmsg.c
+++ b/arch/powerpc/platforms/powernv/opal-kmsg.c
@@ -51,20 +51,17 @@ static void force_opal_console_flush(struct kmsg_dumper *dumper,
 		} while (rc == OPAL_PARTIAL); /* More to flush */
 
 	} else {
-		int i;
+		__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 enough times to flush the buffer.  We don't know
-		 * how much output still needs to be flushed, but we can be
-		 * generous since the kernel is in panic and doesn't need
-		 * to do much else.
+		 * function while it has OPAL_EVENT_CONSOLE_OUTPUT events.
 		 */
-		printk(KERN_NOTICE "opal: OPAL_CONSOLE_FLUSH missing.\n");
-		for (i = 0; i < 1024; i++) {
-			opal_poll_events(NULL);
-		}
+		do {
+			opal_poll_events(&evt);
+		} while (be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT);
 	}
 }
 
-- 
2.17.0

  parent reply	other threads:[~2018-04-30 14:55 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 ` Nicholas Piggin [this message]
2018-05-04  5:16   ` [PATCH 04/15] powerpc/powernv: opal-kmsg use flush fallback from console code Michael Ellerman
2018-05-04  5:37     ` Nicholas Piggin
2018-05-07 10:36       ` Michael Ellerman
2018-05-08  3:40         ` Nicholas Piggin
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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