linux-kernel - Re: [PATCH 26/31] sound/usb: Update ALSA driver to use Managed Media Controller API

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Date:	Thu, 07 Jan 2016 16:44:36 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	"Shuah Khan" <shuahkh@....samsung.com>
Cc:	<hans.verkuil@...co.com>, <laurent.pinchart@...asonboard.com>,
	<clemens@...isch.de>, <sakari.ailus@...ux.intel.com>,
	<javier@....samsung.com>, <mchehab@....samsung.com>,
	<alsa-devel@...a-project.org>, <arnd@...db.de>,
	<ricard.wanderlof@...s.com>, <labbott@...oraproject.org>,
	<chehabrafael@...il.com>, <misterpib@...il.com>,
	<prabhakar.csengg@...il.com>, <ricardo.ribalda@...il.com>,
	<ruchandani.tina@...il.com>, <takamichiho@...il.com>,
	<tvboxspy@...il.com>, <dominic.sacre@....de>, <crope@....fi>,
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	<kyungmin.park@...sung.com>, <m.szyprowski@...sung.com>,
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	<linux-api@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-media@...r.kernel.org>, <linuxbugs@...tgam.net>,
	<gtmkramer@...all.nl>, <normalperson@...t.net>, <daniel@...que.org>
Subject: Re: [PATCH 26/31] sound/usb: Update ALSA driver to use Managed Media Controller API

On Wed, 06 Jan 2016 22:05:35 +0100,
Shuah Khan wrote:
> 
> diff --git a/sound/usb/Makefile b/sound/usb/Makefile
> index 2d2d122..665fdd9 100644
> --- a/sound/usb/Makefile
> +++ b/sound/usb/Makefile
> @@ -2,6 +2,18 @@
>  # Makefile for ALSA
>  #
>  
> +# Media Controller
> +ifeq ($(CONFIG_MEDIA_CONTROLLER),y)
> +  ifeq ($(CONFIG_MEDIA_SUPPORT),y)
> +        KBUILD_CFLAGS += -DUSE_MEDIA_CONTROLLER
> +  endif
> +  ifeq ($(CONFIG_MEDIA_SUPPORT_MODULE),y)
> +    ifeq ($(MODULE),y)
> +          KBUILD_CFLAGS += -DUSE_MEDIA_CONTROLLER
> +    endif
> +  endif
> +endif

Can't we define this rather via Kconfig?
Doing this in Makefile is way too tricky, and it's unclear to users
whether MC is actually enabled or not.


> diff --git a/sound/usb/media.c b/sound/usb/media.c
> new file mode 100644
> index 0000000..747a66a
> --- /dev/null
> +++ b/sound/usb/media.c
> @@ -0,0 +1,214 @@
> +/*
> + * media.c - Media Controller specific ALSA driver code
> + *
> + * Copyright (c) 2015 Shuah Khan <shuahkh@....samsung.com>
> + * Copyright (c) 2015 Samsung Electronics Co., Ltd.
> + *
> + * This file is released under the GPLv2.
> + */
> +
> +/*
> + * This file adds Media Controller support to ALSA driver
> + * to use the Media Controller API to share tuner with DVB
> + * and V4L2 drivers that control media device. Media device
> + * is created based on existing quirks framework. Using this
> + * approach, the media controller API usage can be added for
> + * a specific device.
> +*/
> +
> +#include <linux/init.h>
> +#include <linux/list.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/ctype.h>
> +#include <linux/usb.h>
> +#include <linux/moduleparam.h>
> +#include <linux/mutex.h>
> +#include <linux/usb/audio.h>
> +#include <linux/usb/audio-v2.h>
> +#include <linux/module.h>
> +
> +#include <sound/control.h>
> +#include <sound/core.h>
> +#include <sound/info.h>
> +#include <sound/pcm.h>
> +#include <sound/pcm_params.h>
> +#include <sound/initval.h>
> +
> +#include "usbaudio.h"
> +#include "card.h"
> +#include "midi.h"
> +#include "mixer.h"
> +#include "proc.h"
> +#include "quirks.h"
> +#include "endpoint.h"
> +#include "helper.h"
> +#include "debug.h"
> +#include "pcm.h"
> +#include "format.h"
> +#include "power.h"
> +#include "stream.h"
> +#include "media.h"

I believe we can get rid of many include files just for MC support...


> +#ifdef USE_MEDIA_CONTROLLER

This ifdef can be removed once if we build this object file
conditionally in Makefile.


> @@ -1232,7 +1244,10 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
>  	subs->dsd_dop.channel = 0;
>  	subs->dsd_dop.marker = 1;
>  
> -	return setup_hw_info(runtime, subs);
> +	ret = setup_hw_info(runtime, subs);
> +	if (ret == 0)
> +		ret = media_stream_init(subs, as->pcm, direction);

Need to call snd_usb_autosuspend() in the error path.


> --- a/sound/usb/quirks.c
> +++ b/sound/usb/quirks.c
> @@ -544,13 +545,19 @@ int snd_usb_create_quirk(struct snd_usb_audio *chip,
>  		[QUIRK_AUDIO_ALIGN_TRANSFER] = create_align_transfer_quirk,
>  		[QUIRK_AUDIO_STANDARD_MIXER] = create_standard_mixer_quirk,
>  	};
> +	int ret;
>  
> +	if (quirk->media_device) {
> +		/* don't want to fail when media_device_create() fails */
> +		media_device_create(chip, iface);
> +	}

So far, so good...

>  	if (quirk->type < QUIRK_TYPE_COUNT) {
> -		return quirk_funcs[quirk->type](chip, iface, driver, quirk);
> +		ret = quirk_funcs[quirk->type](chip, iface, driver, quirk);
>  	} else {
>  		usb_audio_err(chip, "invalid quirk type %d\n", quirk->type);
>  		return -ENXIO;
>  	}
> +	return ret;

Any reason to change this?


Takashi
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