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SubjectRe: [PATCH v2] macintosh/via-pmu-led: make disk activity usage a parameter.
Date
Hello,

Hill Ma <maahiuzeon@gmail.com> writes:
> Whether to use the LED as a disk activity is a user preference.
> Some like this usage while others find the LED too bright. So it
> might be a good idea to make this choice a runtime parameter rather
> than compile-time config.

Users already have the ability to change the LED behavior at runtime
already, correct? I.e. they can do:

echo none > /sys/class/leds/pmu-led::front/trigger

in their boot scripts. Granted, a kernel built with ADB_PMU_LED_DISK=y
will blink the LED on disk activity until user space is running. Is this
unsatisfactory?

> The default is set to disabled as OS X does not use the LED as a
> disk activity indicator.

This is long-standing behavior in Linux and OS X has been EOL on this
architecture for a decade, so this isn't much of a consideration at this
point. Seems more important to avoid surprising existing users and
distributions with a behavior change that makes additional work for
them. See below.

> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 43dc35fe5bc0..a656a51ba0a8 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -250,6 +250,12 @@
> Use timer override. For some broken Nvidia NF5 boards
> that require a timer override, but don't have HPET
>
> + adb_pmu_led_disk [PPC]
> + Use front LED as disk LED by default. Only applies to
> + PowerBook, iBook, PowerMac 7,2/7,3.
> + Format: <bool> (1/Y/y=enable, 0/N/n=disable)
> + Default: disabled
> +
> add_efi_memmap [EFI; X86] Include EFI memory map in
> kernel's map of available physical RAM.
>
> diff --git a/drivers/macintosh/Kconfig b/drivers/macintosh/Kconfig
> index 5cdc361da37c..243215de563c 100644
> --- a/drivers/macintosh/Kconfig
> +++ b/drivers/macintosh/Kconfig
> @@ -78,16 +78,6 @@ config ADB_PMU_LED
> behaviour of the old CONFIG_BLK_DEV_IDE_PMAC_BLINK, select this
> and the disk LED trigger and configure appropriately through sysfs.
>
> -config ADB_PMU_LED_DISK
> - bool "Use front LED as DISK LED by default"
> - depends on ADB_PMU_LED
> - depends on LEDS_CLASS
> - select LEDS_TRIGGERS
> - select LEDS_TRIGGER_DISK
> - help
> - This option makes the front LED default to the disk trigger
> - so that it blinks on disk activity.
> -

So, if I've been relying on CONFIG_ADB_PMU_LED_DISK=y and I upgrade to a
newer kernel with the proposed change, from my point of view the disk
activity LED has stopped working and I need to alter the bootloader
config or init scripts to restore the expected behavior. That seems
undesirable to me.

I don't think we rigidly enforce Kconfig backward compatibility, but
when it comes to a user-visible function on a legacy platform where
users and distros likely have their configurations figured out already,
it's probably best to avoid such changes.

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