[PATCH 5.10 326/406] parisc: led: Reduce CPU overhead for disk & lan LED computation

Greg Kroah-Hartman
2023-09-17T19:39:07Z

From: Helge Deller <deller@gmx.de>

commit 358ad816e52d4253b38c2f312e6b1cbd89e0dbf7 upstream.

Older PA-RISC machines have LEDs which show the disk- and LAN-activity.
The computation is done in software and takes quite some time, e.g. on a
J6500 this may take up to 60% time of one CPU if the machine is loaded
via network traffic.

Since most people don't care about the LEDs, start with LEDs disabled and
just show a CPU heartbeat LED. The disk and LAN LEDs can be turned on
manually via /proc/pdc/led.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/parisc/led.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/parisc/led.c
+++ b/drivers/parisc/led.c
@@ -56,8 +56,8 @@
static int led_type __read_mostly = -1;
static unsigned char lastleds; /* LED state from most recent update */
static unsigned int led_heartbeat __read_mostly = 1;
-static unsigned int led_diskio __read_mostly = 1;
-static unsigned int led_lanrxtx __read_mostly = 1;
+static unsigned int led_diskio __read_mostly;
+static unsigned int led_lanrxtx __read_mostly;
static char lcd_text[32] __read_mostly;
static char lcd_text_default[32] __read_mostly;
static int lcd_no_led_support __read_mostly = 0; /* KittyHawk doesn't support LED on its LCD */