Re: [PATCH V1] media: mc-device.c: change media_device_request_alloc to match media_ioctl_info

[Frederic Chen <frederic.chen@mediatek.com>]

Dear Hans,

On Thu, 2020-08-06 at 09:42 +0200, Hans Verkuil wrote:
> On 06/08/2020 09:29, frederic.chen@mediatek.com wrote:
> > From: Frederic Chen <frederic.chen@mediatek.com>
> > 
> > We modified the type of media_device_request_alloc()'s second
> > parameter from int* to void* so that it can match the interface
> > defined in struct media_ioctl_info.
> > 
> > Signed-off-by: Frederic Chen <frederic.chen@mediatek.com>
> > ---
> >  drivers/media/mc/mc-device.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/media/mc/mc-device.c b/drivers/media/mc/mc-device.c
> > index da8088351135..bc5b5ecb6581 100644
> > --- a/drivers/media/mc/mc-device.c
> > +++ b/drivers/media/mc/mc-device.c
> > @@ -370,9 +370,10 @@ static long media_device_get_topology(struct media_device *mdev, void *arg)
> >  	return ret;
> >  }
> >  
> > -static long media_device_request_alloc(struct media_device *mdev,
> > -				       int *alloc_fd)
> > +static long media_device_request_alloc(struct media_device *mdev, void *arg)
> >  {
> > +	int *alloc_fd = arg;
> > +
> >  #ifdef CONFIG_MEDIA_CONTROLLER_REQUEST_API
> >  	if (!mdev->ops || !mdev->ops->req_validate || !mdev->ops->req_queue)
> >  		return -ENOTTY;
> > 
> 
> This change is fine, but the reason this wasn't noticed before is the cast in
> the MEDIA_IOC_ARG define:
> 
> #define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)              \
>         [_IOC_NR(MEDIA_IOC_##__cmd)] = {                                \
>                 .cmd = MEDIA_IOC_##__cmd,                               \
>                 .fn = (long (*)(struct media_device *, void *))func,    \
>                 .flags = fl,                                            \
>                 .arg_from_user = from_user,                             \
>                 .arg_to_user = to_user,                                 \
>         }
> 
> When assigning to .fn the func is cast to a specific function prototype.
> Without that cast the compiler would have warned about the mismatch.
> 
> I see no reason for that cast, so drop that cast as well.

I got it. I will remove the cast in the next patch.

> 
> Regards,
> 
> 	Hans


Sincerely,

Frederic Chen

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