linux-kernel - Re: [PATCH] ARM: OMAP1: ams-delta: Fix audio permanently muted

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Date:   Fri, 7 Dec 2018 08:53:36 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     Janusz Krzysztofik <jmkrzyszt@...il.com>
Cc:     Aaro Koskinen <aaro.koskinen@....fi>,
        linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: OMAP1: ams-delta: Fix audio permanently muted

* Janusz Krzysztofik <jmkrzyszt@...il.com> [181123 03:18]:
> Since commit 1137ceee76ba ("ARM: OMAP1: ams-delta: Don't request unused
> GPIOs"), on-board audio has appeared muted.  Believed to be unused GPIO
> pin "hookflash1", apparently set high regardless of the corresponding
> bit of "latch2" port attempted to be set low during .init_machine(),
> has been identified as the reason.
> 
> According to Amstrad E3 wiki, the purpose of the pin hasn't been
> clearly identified.  Original Amstrad software used to produce a high
> pulse on it when the phone was taken off hook or recall was pressed.
> With the current finding, we can assume the pin provides a kind of
> audio mute function.
> 
> Proper resolution of the issue should be done in two steps:
> - resolution of an issue with the pin state not reflecting the value
>   the corresponding bit of the port was attempted to be initialized
>   with,
> - extension of on-board audio driver with a new control.
> 
> For now, rename the pin to "audio_mute" to reflect its function and,
> as a quick fix, hogg it as output low so on-board audio can produce
> audible sound again.
> 
> Fixes: 1137ceee76ba ("ARM: OMAP1: ams-delta: Don't request unused GPIOs")
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@...il.com>

Adding into omap-for-v4.20/fixes thanks.

Tony