[alsa-devel] [pulseaudio-discuss] ThinkPad T-510 audio output mute LED non-workingness

[Glenn Golden]

Takashi Iwai <tiwai at suse.de> [2015-04-28 12:30:19 +0200]:
> 
> Then it's likely an issue in thinkpad_acpi.c.  It implies that the
> driver couldn't get SSMS acpi handle.
> 

Raymond had pointed this out earlier as a (the?) patch that brought the static
tp_led_table led_tables[] into existence:

    http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/platform/x86/thinkpad_acpi.c?id=420f9739a62cdb027f5580d25c813501ff93aa6f

To my eyes, the table appears to be as it was in that patch:

    ---------------------------------------------------------------------------
    static struct tp_led_table led_tables[] = {
	    [TPACPI_LED_MUTE] = {
		    .name = "SSMS",
		    .on_value = 1,
		    .off_value = 0,
	    },
	    [TPACPI_LED_MICMUTE] = {
		    .name = "MMTS",
		    .on_value = 2,
		    .off_value = 0,
	    },
    };
    ---------------------------------------------------------------------------

thinkpad_acpi.h defines this enum and func:

    ---------------------------------------------------------------------------
    /* These two functions return 0 if success, or negative error code
       (e g -ENODEV if no led present) */

    enum {
	    TPACPI_LED_MUTE,
	    TPACPI_LED_MICMUTE,
	    TPACPI_LED_MAX,
    };

    int tpacpi_led_set(int whichled, bool on);
    ---------------------------------------------------------------------------

although I don't understand why the comment says "these TWO functions..."
since there's only one.

How to learn more about the source of LED_MUTE's evident non-existence in
my build? I guess I don't understand how the above "SSMS" entry in the table
is non-existent? Is there a function-pointer table/hash in which "SSMS" is
further used as a key?

> 
> For HD-audio, you need to unload the codec drivers at first, e.g.
> [ ... ]
>

Thanks, that will help a lot, as the machine is in constant use and
reboots are painful.