On 01/15/2016 06:38 AM, Takashi Iwai wrote:

On Thu, 14 Jan 2016 20:52:28 +0100,
Shuah Khan wrote:

quoted

Change ALSA driver to use Managed Media Managed Controller
API to share tuner with DVB and V4L2 drivers that control
AU0828 media device.  Media device is created based on a
newly added field value in the struct snd_usb_audio_quirk.
Using this approach, the media controller API usage can be
added for a specific device. In this patch, Media Controller
API is enabled for AU0828 hw. snd_usb_create_quirk() will
check this new field, if set will create a media device using
media_device_get_devres() interface.

media_device_get_devres() will allocate a new media device
devres or return an existing one, if it finds one.

During probe, media usb driver could have created the media
device devres. It will then initialze (if necessary) and
register the media device if it isn't already initialized
and registered. Media device unregister is done from
usb_audio_disconnect().

During probe, media usb driver could have created the
media device devres. It will then register the media
device if it isn't already registered. Media device
unregister is done from usb_audio_disconnect().

New structure media_ctl is added to group the new
fields to support media entity and links. This new
structure is added to struct snd_usb_substream.

A new entity_notify hook and a new ALSA capture media
entity are registered from snd_usb_pcm_open() after
setting up hardware information for the PCM device.

When a new entity is registered, Media Controller API
interface media_device_register_entity() invokes all
registered entity_notify hooks for the media device.
ALSA entity_notify hook parses all the entity list to
find a link from decoder it ALSA entity. This indicates
that the bridge driver created a link from decoder to
ALSA capture entity.

ALSA will attempt to enable the tuner to link the tuner
to the decoder calling enable_source handler if one is
provided by the bridge driver prior to starting Media
pipeline from snd_usb_hw_params(). If enable_source returns
with tuner busy condition, then snd_usb_hw_params() will fail
with -EBUSY. Media pipeline is stopped from snd_usb_hw_free().

Signed-off-by: Shuah Khan <redacted>
---
Changes since v1: Addressed Takasi Iwai's comments on v1
- Move config defines to Kconfig and add logic
  to Makefile to conditionally compile media.c
- Removed extra includes from media.c
- Added snd_usb_autosuspend() in error leg
- Removed debug related code that was missed in v1

 sound/usb/Kconfig        |   7 ++
 sound/usb/Makefile       |   4 +
 sound/usb/card.c         |   7 ++
 sound/usb/card.h         |   1 +
 sound/usb/media.c        | 190 +++++++++++++++++++++++++++++++++++++++++++++++
 sound/usb/media.h        |  56 ++++++++++++++
 sound/usb/pcm.c          |  28 +++++--
 sound/usb/quirks-table.h |   1 +
 sound/usb/quirks.c       |   5 ++
 sound/usb/stream.c       |   2 +
 sound/usb/usbaudio.h     |   1 +
 11 files changed, 297 insertions(+), 5 deletions(-)
 create mode 100644 sound/usb/media.c
 create mode 100644 sound/usb/media.h

diff --git a/sound/usb/Kconfig b/sound/usb/Kconfig
index a452ad7..8d5cdab 100644
--- a/sound/usb/Kconfig
+++ b/sound/usb/Kconfig

@@ -15,6 +15,7 @@ config SND_USB_AUDIO
 	select SND_RAWMIDI
 	select SND_PCM
 	select BITREVERSE
+	select SND_USB_AUDIO_USE_MEDIA_CONTROLLER if MEDIA_CONTROLLER && (MEDIA_SUPPORT || MEDIA_SUPPORT_MODULE)

This looks wrong as a Kconfig syntax.  "... if MEDIA_CONTROLLER"
should work, I suppose?

The conditional select syntax is used in several Kconfig
files. You are right about (MEDIA_SUPPORT || MEDIA_SUPPORT_MODULE)
Adding checks for that is unnecessary.

Above all, can MEDIA_CONTROLLER be tristate?  It's currently a bool.
If it's a tristate, it causes a problem wrt dependency.  Imagine
USB-audio is built-in while MC is a module.

I don't think MEDIA_CONTROLLER will evebr tristate. I have this
logic to the following and it works with and without MEDIA_CONTROLLER

diff --git a/sound/usb/Kconfig b/sound/usb/Kconfig
index a452ad7..8ccbb35 100644
--- a/sound/usb/Kconfig
+++ b/sound/usb/Kconfig

@@ -15,6 +15,7 @@ config SND_USB_AUDIO
        select SND_RAWMIDI
        select SND_PCM
        select BITREVERSE
+       select SND_USB_AUDIO_USE_MEDIA_CONTROLLER       if MEDIA_CONTROLLER
        help
          Say Y here to include support for USB audio and USB MIDI
          devices.

@@ -22,6 +23,11 @@ config SND_USB_AUDIO
          To compile this driver as a module, choose M here: the module
          will be called snd-usb-audio.

+config SND_USB_AUDIO_USE_MEDIA_CONTROLLER
+       bool "USB Audio/MIDI driver with Media Controller Support"
+       depends on MEDIA_CONTROLLER
+       default y
+

quoted

 	help
 	  Say Y here to include support for USB audio and USB MIDI
 	  devices.

@@ -22,6 +23,12 @@ config SND_USB_AUDIO
 	  To compile this driver as a module, choose M here: the module
 	  will be called snd-usb-audio.
 
+config SND_USB_AUDIO_USE_MEDIA_CONTROLLER
+	bool "USB Audio/MIDI driver with Media Controller Support"
+	depends on SND_USB_AUDIO && MEDIA_CONTROLLER
+	depends on MEDIA_SUPPORT || MEDIA_SUPPORT_MODULE

See above. I got rid of depends on for SND_USB_AUDIO

Hmm, it's superfluous to have both this depends and the reverse-select
of the above.  (And again MEDIA_SUPPORT_MODULE looks bogus.)

quoted

+	default y
+
 config SND_USB_UA101
 	tristate "Edirol UA-101/UA-1000 driver"
 	select SND_PCM

diff --git a/sound/usb/Makefile b/sound/usb/Makefile
index 2d2d122..3113c45 100644
--- a/sound/usb/Makefile
+++ b/sound/usb/Makefile

@@ -15,6 +15,10 @@ snd-usb-audio-objs := 	card.o \
 			quirks.o \
 			stream.o
 
+ifeq ($(CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER),y)
+  snd-usb-audio-objs += media.o
+endif

A better form is like

snd-usb-audio-$(CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER) += media.

Got it. Fixed it now.

quoted

+
 snd-usbmidi-lib-objs := midi.o
 
 # Toplevel Module Dependency

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 18f5664..1a63851 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c

@@ -66,6 +66,7 @@
 #include "format.h"
 #include "power.h"
 #include "stream.h"
+#include "media.h"
 
 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
 MODULE_DESCRIPTION("USB Audio");

@@ -621,6 +622,12 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 		list_for_each_entry(mixer, &chip->mixer_list, list) {
 			snd_usb_mixer_disconnect(mixer);
 		}
+		/*
+		 * Nice to check quirk && quirk->media_device
+		 * need some special handlings. Doesn't look like
+		 * we have access to quirk here
+		*/
+		media_device_delete(intf);
 	}
 
 	chip->num_interfaces--;

diff --git a/sound/usb/card.h b/sound/usb/card.h
index 71778ca..c15a03c 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h

@@ -156,6 +156,7 @@ struct snd_usb_substream {
 	} dsd_dop;
 
 	bool trigger_tstamp_pending_update; /* trigger timestamp being updated from initial estimate */
+	void *media_ctl;
 };
 
 struct snd_usb_stream {

diff --git a/sound/usb/media.c b/sound/usb/media.c
new file mode 100644
index 0000000..644b6e8
--- /dev/null
+++ b/sound/usb/media.c

@@ -0,0 +1,190 @@
+/*
+ * media.c - Media Controller specific ALSA driver code
+ *
+ * Copyright (c) 2015 Shuah Khan <shuahkh@osg.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/mutex.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include <sound/pcm.h>
+
+#include "usbaudio.h"
+#include "card.h"
+#include "media.h"
+
+int media_device_create(struct snd_usb_audio *chip,
+			struct usb_interface *iface)
+{
+	struct media_device *mdev;
+	struct usb_device *usbdev = interface_to_usbdev(iface);
+	int ret;
+
+	mdev = media_device_get_devres(&usbdev->dev);
+	if (!mdev)
+		return -ENOMEM;
+	if (!mdev->dev) {
+		/* register media device */
+		mdev->dev = &usbdev->dev;
+		if (usbdev->product)
+			strlcpy(mdev->model, usbdev->product,
+				sizeof(mdev->model));
+		if (usbdev->serial)
+			strlcpy(mdev->serial, usbdev->serial,
+				sizeof(mdev->serial));
+		strcpy(mdev->bus_info, usbdev->devpath);
+		mdev->hw_revision = le16_to_cpu(usbdev->descriptor.bcdDevice);
+		ret = media_device_init(mdev);
+		if (ret) {
+			dev_err(&usbdev->dev,
+				"Couldn't create a media device. Error: %d\n",
+				ret);
+			return ret;
+		}
+	}
+	if (!media_devnode_is_registered(&mdev->devnode)) {
+		ret = media_device_register(mdev);
+		if (ret) {
+			dev_err(&usbdev->dev,
+				"Couldn't register media device. Error: %d\n",
+				ret);
+			return ret;
+		}
+	}
+	return 0;
+}
+
+void media_device_delete(struct usb_interface *iface)
+{
+	struct media_device *mdev;
+	struct usb_device *usbdev = interface_to_usbdev(iface);
+
+	mdev = media_device_find_devres(&usbdev->dev);
+	if (mdev && media_devnode_is_registered(&mdev->devnode))
+		media_device_unregister(mdev);
+}
+
+static int media_enable_source(struct media_ctl *mctl)
+{
+	if (mctl && mctl->media_dev->enable_source)
+		return mctl->media_dev->enable_source(&mctl->media_entity,
+						      &mctl->media_pipe);
+	return 0;
+}
+
+static void media_disable_source(struct media_ctl *mctl)
+{
+	if (mctl && mctl->media_dev->disable_source)
+		mctl->media_dev->disable_source(&mctl->media_entity);
+}
+
+int media_stream_init(struct snd_usb_substream *subs, struct snd_pcm *pcm,
+			int stream)
+{
+	struct media_device *mdev;
+	struct media_ctl *mctl;
+	struct device *pcm_dev = &pcm->streams[stream].dev;
+	u32 intf_type;
+	int ret = 0;
+
+	mdev = media_device_find_devres(&subs->dev->dev);
+	if (!mdev)
+		return -ENODEV;
+
+	if (subs->media_ctl)
+		return 0;
+
+	/* allocate media_ctl */
+	mctl = kzalloc(sizeof(*mctl), GFP_KERNEL);
+	if (!mctl)
+		return -ENOMEM;
+
+	mctl->media_dev = mdev;
+	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		intf_type = MEDIA_INTF_T_ALSA_PCM_PLAYBACK;
+		mctl->media_entity.function = MEDIA_ENT_F_AUDIO_PLAYBACK;
+	} else {
+		intf_type = MEDIA_INTF_T_ALSA_PCM_CAPTURE;
+		mctl->media_entity.function = MEDIA_ENT_F_AUDIO_CAPTURE;
+	}
+	mctl->media_entity.name = pcm->name;
+	mctl->media_entity.info.dev.major = MAJOR(pcm_dev->devt);
+	mctl->media_entity.info.dev.minor = MINOR(pcm_dev->devt);
+	mctl->media_pad.flags = MEDIA_PAD_FL_SINK;
+	media_entity_pads_init(&mctl->media_entity, 1, &mctl->media_pad);
+	ret =  media_device_register_entity(mctl->media_dev,
+					    &mctl->media_entity);
+	if (ret) {
+		kfree(mctl);
+		return ret;
+	}
+	mctl->intf_devnode = media_devnode_create(mdev, intf_type, 0,
+						  MAJOR(pcm_dev->devt),
+						  MINOR(pcm_dev->devt));
+	if (!mctl->intf_devnode) {
+		media_device_unregister_entity(&mctl->media_entity);
+		kfree(mctl);
+		return -ENOMEM;
+	}
+	mctl->intf_link = media_create_intf_link(&mctl->media_entity,
+						 &mctl->intf_devnode->intf,
+						 MEDIA_LNK_FL_ENABLED);
+	if (!mctl->intf_link) {
+		media_devnode_remove(mctl->intf_devnode);
+		media_device_unregister_entity(&mctl->media_entity);
+		kfree(mctl);
+		return -ENOMEM;
+	}
+	subs->media_ctl = (void *) mctl;

The cast to a void pointer is superfluous.

Right. Fixed it and couple of others like this
one I found.

Will send v3 shortly.

thanks,
-- Shuah

-- 
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@osg.samsung.com | (970) 217-8978