Re: [PATCH 1/4] ASoC: sun4i-codec: Add support for PA gpio pin

From: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
To: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Liam Girdwood <lgirdwood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Jaroslav Kysela <perex-/Fr2/VpizcU@public.gmane.org>,
	Takashi Iwai <tiwai-IBi9RG/b67k@public.gmane.org>,
	Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>,
	alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
Subject: Re: [PATCH 1/4] ASoC: sun4i-codec: Add support for PA gpio pin
Date: Fri, 20 Nov 2015 17:30:47 +0100	[thread overview]
Message-ID: <20151120163047.GF32142@lukather> (raw)
In-Reply-To: <1448027233-750-1-git-send-email-hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

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On Fri, Nov 20, 2015 at 02:47:10PM +0100, Hans de Goede wrote:
> Add support for PA gpio pin for controlling an external amplifier as used
> on some Allwinner boards.
> 
> Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  .../devicetree/bindings/sound/sun4i-codec.txt      |  3 +++
>  sound/soc/sunxi/sun4i-codec.c                      | 25 ++++++++++++++--------
>  2 files changed, 19 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/sound/sun4i-codec.txt b/Documentation/devicetree/bindings/sound/sun4i-codec.txt
> index c92966b..974babe 100644
> --- a/Documentation/devicetree/bindings/sound/sun4i-codec.txt
> +++ b/Documentation/devicetree/bindings/sound/sun4i-codec.txt
> @@ -14,6 +14,9 @@ Required properties:
>     - "apb": the parent APB clock for this controller
>     - "codec": the parent module clock
>  
> +Optional properties:
> +- pa-gpios: gpio to enable external amplifier

This is a custom property, it should be prefixed by the vendor name.

> +
>  Example:
>  codec: codec@01c22c00 {
>  	#sound-dai-cells = <0>;
> diff --git a/sound/soc/sunxi/sun4i-codec.c b/sound/soc/sunxi/sun4i-codec.c
> index bcbf4da..2aca9cd 100644
> --- a/sound/soc/sunxi/sun4i-codec.c
> +++ b/sound/soc/sunxi/sun4i-codec.c
> @@ -27,6 +27,7 @@
>  #include <linux/of_address.h>
>  #include <linux/clk.h>
>  #include <linux/regmap.h>
> +#include <linux/gpio/consumer.h>
>  
>  #include <sound/core.h>
>  #include <sound/pcm.h>
> @@ -101,16 +102,15 @@ struct sun4i_codec {
>  	struct regmap	*regmap;
>  	struct clk	*clk_apb;
>  	struct clk	*clk_module;
> +	struct gpio_desc *gpio_pa;
>  
>  	struct snd_dmaengine_dai_dma_data	playback_dma_data;
>  };
>  
>  static void sun4i_codec_start_playback(struct sun4i_codec *scodec)
>  {
> -	/*
> -	 * FIXME: according to the BSP, we might need to drive a PA
> -	 *        GPIO high here on some boards
> -	 */
> +	if (scodec->gpio_pa)
> +		gpiod_set_value_cansleep(scodec->gpio_pa, 1);
>  
>  	/* Flush TX FIFO */
>  	regmap_update_bits(scodec->regmap, SUN4I_CODEC_DAC_FIFOC,
> @@ -125,15 +125,13 @@ static void sun4i_codec_start_playback(struct sun4i_codec *scodec)
>  
>  static void sun4i_codec_stop_playback(struct sun4i_codec *scodec)
>  {
> -	/*
> -	 * FIXME: according to the BSP, we might need to drive a PA
> -	 *        GPIO low here on some boards
> -	 */
> -
>  	/* Disable DAC DRQ */
>  	regmap_update_bits(scodec->regmap, SUN4I_CODEC_DAC_FIFOC,
>  			   BIT(SUN4I_CODEC_DAC_FIFOC_DAC_DRQ_EN),
>  			   0);
> +
> +	if (scodec->gpio_pa)
> +		gpiod_set_value_cansleep(scodec->gpio_pa, 0);

You should rather plug that into DAPM, using a speaker widget, and a
custom event function that will enable or disable the amplifier only
when this audio path is going to be used.

You can see such an example here:
http://lxr.free-electrons.com/source/sound/soc/jz4740/qi_lb60.c#L29

That will require to modify a bit sun4i_codec_create_card as well in
order to add the new widgets (and routes) when the DT property is
found.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com