Re: [PATCH v4 21/29] media: mc: Don't care about unsettable flags in MEDIA_IOC_LINK_SETUP

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Laurent,

On Thu, Apr 16, 2026 at 06:59:17PM +0300, Laurent Pinchart wrote:
> Hi Sakari,
> 
> Thank you for the patch.
> 
> On Wed, Apr 08, 2026 at 06:39:30PM +0300, Sakari Ailus wrote:
> > The implementation of MEDIA_IOC_LINK_SETUP currently requires that all
> > flags that are set by the driver are correctly set as the driver expects.
> > This poses a problem for adding new flags as programs could not work with
> > links that have unknown flags even when the use of these flags wouldn't
> > affect the program.
> 
> I suppose applications could be instructed to preserve the flags they
> don't know about, but some existing applications probably don't do that.
> 
> > Ignore the non-settable link flags.
> > 
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  drivers/media/mc/mc-entity.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
> > index 717569bd1a8c..287eded356bb 100644
> > --- a/drivers/media/mc/mc-entity.c
> > +++ b/drivers/media/mc/mc-entity.c
> > @@ -1319,7 +1319,7 @@ static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
> >  
> >  int __media_entity_setup_link(struct media_link *link, u32 flags)
> >  {
> > -	const u32 mask = MEDIA_LNK_FL_ENABLED;
> > +	const u32 settable_flags = MEDIA_LNK_FL_ENABLED;
> >  	struct media_device *mdev;
> >  	struct media_pad *source, *sink;
> >  	int ret = -EBUSY;
> > @@ -1327,9 +1327,9 @@ int __media_entity_setup_link(struct media_link *link, u32 flags)
> >  	if (link == NULL)
> >  		return -EINVAL;
> >  
> > -	/* The non-modifiable link flags must not be modified. */
> > -	if ((link->flags & ~mask) != (flags & ~mask))
> > -		return -EINVAL;
> > +	/* Only allow changing user-settable flags. */
> > +	flags &= settable_flags;
> > +	flags |= link->flags & ~settable_flags;
> 
> Now that the link can be configured with different flags than the ones
> set by userspace, I think the ioctl should return the actual link flags.

I'll do that for v5.

> 
> >  
> >  	if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
> >  		return link->flags == flags ? 0 : -EINVAL;
> 

-- 
Regards,

Sakari Ailus