linux-kernel - Re: [PATCH v5 22/22] sound/usb: Use Media Controller API to share media resources

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Date:	Wed, 2 Mar 2016 23:41:31 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Shuah Khan <shuahkh@....samsung.com>
Cc:	mchehab@....samsung.com, tiwai@...e.com, clemens@...isch.de,
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Subject: Re: [PATCH v5 22/22] sound/usb: Use Media Controller API to share
 media resources

On Wed, Mar 02, 2016 at 09:50:31AM -0700, Shuah Khan wrote:
> +	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;
> +		mctl->media_pad.flags = MEDIA_PAD_FL_SOURCE;
> +		mixer_pad = 1;
> +	} else {
> +		intf_type = MEDIA_INTF_T_ALSA_PCM_CAPTURE;
> +		mctl->media_entity.function = MEDIA_ENT_F_AUDIO_CAPTURE;
> +		mctl->media_pad.flags = MEDIA_PAD_FL_SINK;
> +		mixer_pad = 2;
> +	}
> +	mctl->media_entity.name = pcm->name;
> +	media_entity_pads_init(&mctl->media_entity, 1, &mctl->media_pad);
> +	ret =  media_device_register_entity(mctl->media_dev,
> +					    &mctl->media_entity);
> +	if (ret)
> +		goto err1;

Could we give this label a meaningful name instead of a number?
goto free_mctl;

> +
> +	mctl->intf_devnode = media_devnode_create(mdev, intf_type, 0,
> +						  MAJOR(pcm_dev->devt),
> +						  MINOR(pcm_dev->devt));
> +	if (!mctl->intf_devnode) {
> +		ret = -ENOMEM;
> +		goto err2;

goto unregister_device;

> +	}
> +	mctl->intf_link = media_create_intf_link(&mctl->media_entity,
> +						 &mctl->intf_devnode->intf,
> +						 MEDIA_LNK_FL_ENABLED);
> +	if (!mctl->intf_link) {
> +		ret = -ENOMEM;
> +		goto err3;

goto delete_devnode;

> +	}
> +
> +	/* create link between mixer and audio */
> +	media_device_for_each_entity(entity, mdev) {
> +		switch (entity->function) {
> +		case MEDIA_ENT_F_AUDIO_MIXER:
> +			ret = media_create_pad_link(entity, mixer_pad,
> +						    &mctl->media_entity, 0,
> +						    MEDIA_LNK_FL_ENABLED);
> +			if (ret)
> +				goto err4;

This is a bit weird because we're inside a loop.  Shouldn't we call
media_entity_remove_links() or something if this is the second time
through the loop?

I don't understand this.  The kernel has the media_entity_cleanup() stub
function which is supposed to do this but it hasn't been implemented
yet?

regards,
dan carpenter