powerpc/powernv: opal-kmsg use flush fallback from console code

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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c b/arch/powerpc/platforms/powernv/opal-kmsg.c
index f8f41cc..fd2bbf4 100644 (file)
--- 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);
        }
 }