From 36d2dabc8762f1f4118f80d85049958390f061a8 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Tue, 1 May 2018 00:55:45 +1000 Subject: [PATCH] powerpc/powernv: Fix OPAL console driver OPAL_BUSY loops The OPAL console driver does not delay in case it gets OPAL_BUSY or OPAL_BUSY_EVENT from firmware. It can't yet be made to sleep because it is called under spinlock, but it can be changed to the standard OPAL_BUSY loop form, and a delay added to keep it from hitting the firmware too frequently. Cc: Benjamin Herrenschmidt Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/platforms/powernv/opal.c | 38 +++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c index 371e33e..a9773a6 100644 --- a/arch/powerpc/platforms/powernv/opal.c +++ b/arch/powerpc/platforms/powernv/opal.c @@ -378,33 +378,41 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) /* We still try to handle partial completions, though they * should no longer happen. */ - rc = OPAL_BUSY; - while(total_len > 0 && (rc == OPAL_BUSY || - rc == OPAL_BUSY_EVENT || rc == OPAL_SUCCESS)) { + + while (total_len > 0) { olen = cpu_to_be64(total_len); - rc = opal_console_write(vtermno, &olen, data); + + rc = OPAL_BUSY; + while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) { + rc = opal_console_write(vtermno, &olen, data); + if (rc == OPAL_BUSY_EVENT) { + mdelay(OPAL_BUSY_DELAY_MS); + opal_poll_events(NULL); + } else if (rc == OPAL_BUSY) { + mdelay(OPAL_BUSY_DELAY_MS); + } + } + len = be64_to_cpu(olen); /* Closed or other error drop */ - if (rc != OPAL_SUCCESS && rc != OPAL_BUSY && - rc != OPAL_BUSY_EVENT) { - written += total_len; + if (rc != OPAL_SUCCESS) { + written += total_len; /* drop remaining chars */ break; } - if (rc == OPAL_SUCCESS) { - total_len -= len; - data += len; - written += len; - } + + total_len -= len; + data += len; + written += len; + /* 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 */ - do + do { opal_poll_events(&evt); - while(rc == OPAL_SUCCESS && - (be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT)); + } while (be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT); } spin_unlock_irqrestore(&opal_write_lock, flags); return written; -- 2.7.4