linux-kernel - Re: [PATCH] ALSA: hda/realtek: Enable HP amp and mute LED on HP Folio 9480m

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Date:	Tue, 14 Jul 2015 19:37:44 -0700
From:	Keith Packard <keithp@...thp.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Jaroslav Kysela <perex@...ex.cz>,
	Kailang Yang <kailang@...ltek.com>,
	Hui Wang <hui.wang@...onical.com>,
	David Henningsson <david.henningsson@...onical.com>,
	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: hda/realtek: Enable HP amp and mute LED on HP Folio 9480m

Takashi Iwai <tiwai@...e.de> writes:

> Thanks for the patch.  But this looks suboptimal, unfortunately, since
> it keeps the amp always on, and more badly, it would block the power
> save of the widget root node.

Thanks very much for your feedback; I wasn't sure precisely how this
code worked and tried to make a change that was as close as I could
manage to existing examples.

> Can just using gpio_mute_led_mask=0x18 and gpio_led=0 (also drop
> AC_VERB_SET_GPIO_DATA in gpio_init[]) work instead?  If GPIO4 is the
> the amp, we can associate it with the master mute control together
> with the mute LED.  The only concern would be the possible click
> noise, but it doesn't happen on most machines.

It's not quite that simple; the GPIO4 value is inverted from the mute
LED value (the amp is powered up when GPIO4 is set).

What I've done is to make the amp powered only when a headphone is
plugged in, and then removed the code which was disabling power saving,
which lets everything (including the amp) get turned back off when the
device goes idle.

Here's a second version of the patch.

View attachment "0001-ALSA-hda-realtek-Enable-HP-amp-and-mute-LED-on-HP-Fo.patch" of type "text/x-diff" (5355 bytes)

-- 
-keith

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