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Subject[PATCH 07/15] powerpc/powernv: move opal console flushing to udbg
Date
OPAL console writes do not have to synchronously flush firmware /
hardware buffers unless they are going through the udbg path.

Remove the unconditional flushing from opal_put_chars. Flush if
there was no space in the buffer as an optimisation (callers loop
waiting for success in that case). udbg flushing is moved to
udbg_opal_putc.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/platforms/powernv/opal.c | 12 +++++++-----
drivers/tty/hvc/hvc_opal.c | 5 +++++
2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 0ddb63226695..55d4b1983110 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -400,12 +400,14 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len)
out:
spin_unlock_irqrestore(&opal_write_lock, flags);

- /* This is a bit nasty but we need that for the console to
- * flush when there aren't any interrupts. We will clean
- * things a bit later to limit that to synchronous path
- * such as the kernel console and xmon/udbg
+ /* In the -EAGAIN case, callers loop, so we have to flush the console
+ * here in case they have interrupts off (and we don't want to wait
+ * for async flushing if we can make immediate progress here). If
+ * necessary the API could be made entirely non-flushing if the
+ * callers had a ->flush API to use.
*/
- opal_flush_console(vtermno);
+ if (written == -EAGAIN)
+ opal_flush_console(vtermno);

return written;
}
diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c
index 2ed07ca6389e..af122ad7f06d 100644
--- a/drivers/tty/hvc/hvc_opal.c
+++ b/drivers/tty/hvc/hvc_opal.c
@@ -275,6 +275,11 @@ static void udbg_opal_putc(char c)
count = hvc_opal_hvsi_put_chars(termno, &c, 1);
break;
}
+
+ /* This is needed for the cosole to flush
+ * when there aren't any interrupts.
+ */
+ opal_flush_console(termno);
} while(count == 0 || count == -EAGAIN);
}

--
2.17.0
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