linux-kernel - Re: [PATCH v2 14/22] media: au0828 change to use Managed Media Controller API

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Date:	Thu, 4 Feb 2016 08:08:50 -0200
From:	Mauro Carvalho Chehab <mchehab@....samsung.com>
To:	Shuah Khan <shuahkh@....samsung.com>
Cc:	tiwai@...e.com, clemens@...isch.de, hans.verkuil@...co.com,
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	linux-api@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: [PATCH v2 14/22] media: au0828 change to use Managed Media
 Controller API

Em Thu, 4 Feb 2016 08:05:00 -0200
Mauro Carvalho Chehab <mchehab@....samsung.com> escreveu:

> Em Wed, 03 Feb 2016 21:03:46 -0700
> Shuah Khan <shuahkh@....samsung.com> escreveu:
> 
> > Change au0828 to use Managed Media Controller API to
> > share media device and coordinate creating/deleting
> > the shared media device with the snd-usb-audio driver.
> > The shared media device is created as device resource
> > of the parent usb device of the two drivers.
> > 
> > Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
> > ---
> >  drivers/media/usb/au0828/au0828-core.c | 29 +++++++++++++++--------------
> >  1 file changed, 15 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/media/usb/au0828/au0828-core.c b/drivers/media/usb/au0828/au0828-core.c
> > index df2bc3f..b8c4bdd 100644
> > --- a/drivers/media/usb/au0828/au0828-core.c
> > +++ b/drivers/media/usb/au0828/au0828-core.c
> > @@ -134,10 +134,10 @@ static void au0828_unregister_media_device(struct au0828_dev *dev)
> >  {
> >  
> >  #ifdef CONFIG_MEDIA_CONTROLLER
> > -	if (dev->media_dev) {
> > +	if (dev->media_dev &&
> > +		media_devnode_is_registered(&dev->media_dev->devnode)) {
> >  		media_device_unregister(dev->media_dev);
> >  		media_device_cleanup(dev->media_dev);
> > -		kfree(dev->media_dev);
> >  		dev->media_dev = NULL;
> >  	}
> >  #endif
> > @@ -223,23 +223,24 @@ static int au0828_media_device_init(struct au0828_dev *dev,
> >  #ifdef CONFIG_MEDIA_CONTROLLER
> >  	struct media_device *mdev;
> >  
> > -	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
> > +	mdev = media_device_get_devres(&udev->dev);
> >  	if (!mdev)
> >  		return -ENOMEM;
> >  
> > -	mdev->dev = &udev->dev;
> > +	if (!media_devnode_is_registered(&mdev->devnode)) {
> > +		mdev->dev = &udev->dev;
> >  
> > -	if (!dev->board.name)
> > -		strlcpy(mdev->model, "unknown au0828", sizeof(mdev->model));
> > -	else
> > -		strlcpy(mdev->model, dev->board.name, sizeof(mdev->model));
> > -	if (udev->serial)
> > -		strlcpy(mdev->serial, udev->serial, sizeof(mdev->serial));
> > -	strcpy(mdev->bus_info, udev->devpath);
> > -	mdev->hw_revision = le16_to_cpu(udev->descriptor.bcdDevice);
> > -	mdev->driver_version = LINUX_VERSION_CODE;
> > +		if (udev->product)
> > +			strlcpy(mdev->model, udev->product,
> > +				sizeof(mdev->model));
> 
> Why did you change that? On some boards, udev->product doesn't reflect
> the brand name, but have just some random generic data.
> 
> Also, as the other logs associated with the device uses dev->board.name,
> we want the media controller to use the same name here. Ok, if this
> is null, we could use udev->product as a replacement.

Ah, looking at patch 15/22, I understood why you wanted the above
change: if the device is registered first by ALSA, it won't have a
dev->board.name.

It looks OK to change from dev->board.name to udev->product then,
but please document the reason for it at the patch description.

Regards,
Mauro