Re: [PATCH 1/3] parisc: led: Reduce CPU overhead for disk & lan LED computation

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Aug 25, 2023 at 08:09:26PM +0200, deller@kernel.org wrote:
> From: Helge Deller <deller@gmx.de>
> 
> 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>
> ---
>  drivers/parisc/led.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/parisc/led.c b/drivers/parisc/led.c
> index 8bdc5e043831..765f19608f60 100644
> --- 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 */
> @@ -589,6 +589,9 @@ int __init register_led_driver(int model, unsigned long cmd_reg, unsigned long d
>  		return 1;
>  	}
>  	
> +	pr_info("LED: Enable disk and LAN activity LEDs "
> +		"via /proc/pdc/led\n");

When drivers are working properly, they should be quiet.  Who is going
to see this message?

I don't even understand it, are you saying that you now need to go
enable the led through proc?  And why are leds in proc, I thought they
had a real class for them?  Why not use that instead?

And finally, you shouldn't split strings across lines :)

thanks,

greg k-h