Re: [PATCH v2 02/13] media: v4l2: async: Allow searching for asd of any type

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Hi Steve,

Thanks for the patchset. Please see my comments below.

On Sat, Mar 10, 2018 at 11:58:31AM -0800, Steve Longerbeam wrote:
> Generalize v4l2_async_notifier_fwnode_has_async_subdev() to allow
> searching for any type of async subdev, not just fwnodes. Rename to
> v4l2_async_notifier_has_async_subdev() and pass it an asd pointer.
> 
> TODO: support asd compare with CUSTOM match type in asd_equal().

Right now there's a recognised need to have multiple fwnodes (endpoints)
per sub-device. The current APIs (when it comes to the firmware interface)
support this with fwnode but not with other async match types.

Just FYI.

> 
> Signed-off-by: Steve Longerbeam <steve_longerbeam@xxxxxxxxxx>
> ---
>  drivers/media/v4l2-core/v4l2-async.c | 86 +++++++++++++++++++++++-------------
>  1 file changed, 56 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> index 2b08d03..c083efa 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -124,6 +124,42 @@ static struct v4l2_async_subdev *v4l2_async_find_match(
>  	return NULL;
>  }
>  
> +/* Compare two asd's for equivalence */
> +static bool asd_equal(struct v4l2_async_subdev *asd_x,
> +		      struct v4l2_async_subdev *asd_y)
> +{
> +	bool ret = false;
> +
> +	if (!asd_x || !asd_y)

Can this happen?

> +		return false;

How about checking here that the match_type ... matches? You could remove
that check elsewhere in the function.

You could also easily do without ret variable.

> +
> +	switch (asd_x->match_type) {
> +	case V4L2_ASYNC_MATCH_DEVNAME:
> +		if (asd_y->match_type == V4L2_ASYNC_MATCH_DEVNAME)
> +			ret = !strcmp(asd_x->match.device_name,
> +				      asd_y->match.device_name);
> +		break;
> +	case V4L2_ASYNC_MATCH_I2C:
> +		if (asd_y->match_type == V4L2_ASYNC_MATCH_I2C)
> +			ret = (asd_x->match.i2c.adapter_id ==
> +			       asd_y->match.i2c.adapter_id &&
> +			       asd_x->match.i2c.address ==
> +			       asd_y->match.i2c.address);
> +		break;
> +	case V4L2_ASYNC_MATCH_FWNODE:
> +		if (asd_y->match_type == V4L2_ASYNC_MATCH_FWNODE)
> +			ret = (asd_x->match.fwnode == asd_y->match.fwnode);
> +		break;
> +	case V4L2_ASYNC_MATCH_CUSTOM:
> +		/* TODO */
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
>  /* Find the sub-device notifier registered by a sub-device driver. */
>  static struct v4l2_async_notifier *v4l2_async_find_subdev_notifier(
>  	struct v4l2_subdev *sd)
> @@ -308,18 +344,15 @@ static void v4l2_async_notifier_unbind_all_subdevs(
>  	notifier->parent = NULL;
>  }
>  
> -/* See if an fwnode can be found in a notifier's lists. */
> -static bool __v4l2_async_notifier_fwnode_has_async_subdev(
> -	struct v4l2_async_notifier *notifier, struct fwnode_handle *fwnode)
> +/* See if an async sub-device can be found in a notifier's lists. */
> +static bool __v4l2_async_notifier_has_async_subdev(
> +	struct v4l2_async_notifier *notifier, struct v4l2_async_subdev *asd)
>  {
> -	struct v4l2_async_subdev *asd;
> +	struct v4l2_async_subdev *asd_y;
>  	struct v4l2_subdev *sd;
>  
> -	list_for_each_entry(asd, &notifier->waiting, list) {
> -		if (asd->match_type != V4L2_ASYNC_MATCH_FWNODE)
> -			continue;
> -
> -		if (asd->match.fwnode == fwnode)
> +	list_for_each_entry(asd_y, &notifier->waiting, list) {
> +		if (asd_equal(asd, asd_y))
>  			return true;
>  	}

You no longer need the braces here.

>  
> @@ -327,10 +360,7 @@ static bool __v4l2_async_notifier_fwnode_has_async_subdev(
>  		if (WARN_ON(!sd->asd))
>  			continue;
>  
> -		if (sd->asd->match_type != V4L2_ASYNC_MATCH_FWNODE)
> -			continue;
> -
> -		if (sd->asd->match.fwnode == fwnode)
> +		if (asd_equal(asd, sd->asd))
>  			return true;
>  	}
>  
> @@ -338,33 +368,30 @@ static bool __v4l2_async_notifier_fwnode_has_async_subdev(
>  }
>  
>  /*
> - * Find out whether an async sub-device was set up for an fwnode already or
> + * Find out whether an async sub-device was set up already or
>   * whether it exists in a given notifier before @this_index.
>   */
> -static bool v4l2_async_notifier_fwnode_has_async_subdev(
> -	struct v4l2_async_notifier *notifier, struct fwnode_handle *fwnode,
> +static bool v4l2_async_notifier_has_async_subdev(
> +	struct v4l2_async_notifier *notifier, struct v4l2_async_subdev *asd,
>  	unsigned int this_index)
>  {
>  	unsigned int j;
>  
>  	lockdep_assert_held(&list_lock);
>  
> -	/* Check that an fwnode is not being added more than once. */
> +	/* Check that an asd is not being added more than once. */
>  	for (j = 0; j < this_index; j++) {
> -		struct v4l2_async_subdev *asd = notifier->subdevs[this_index];
> -		struct v4l2_async_subdev *other_asd = notifier->subdevs[j];
> +		struct v4l2_async_subdev *asd_y = notifier->subdevs[j];
>  
> -		if (other_asd->match_type == V4L2_ASYNC_MATCH_FWNODE &&
> -		    asd->match.fwnode ==
> -		    other_asd->match.fwnode)
> +		if (asd_equal(asd, asd_y))
>  			return true;
>  	}
>  
> -	/* Check than an fwnode did not exist in other notifiers. */
> -	list_for_each_entry(notifier, &notifier_list, list)
> -		if (__v4l2_async_notifier_fwnode_has_async_subdev(
> -			    notifier, fwnode))
> +	/* Check that an asd does not exist in other notifiers. */
> +	list_for_each_entry(notifier, &notifier_list, list) {
> +		if (__v4l2_async_notifier_has_async_subdev(notifier, asd))
>  			return true;
> +	}

You don't really need braces here.

>  
>  	return false;
>  }
> @@ -392,12 +419,11 @@ static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
>  		case V4L2_ASYNC_MATCH_CUSTOM:
>  		case V4L2_ASYNC_MATCH_DEVNAME:
>  		case V4L2_ASYNC_MATCH_I2C:
> -			break;
>  		case V4L2_ASYNC_MATCH_FWNODE:
> -			if (v4l2_async_notifier_fwnode_has_async_subdev(
> -				    notifier, asd->match.fwnode, i)) {
> +			if (v4l2_async_notifier_has_async_subdev(
> +				    notifier, asd, i)) {
>  				dev_err(dev,
> -					"fwnode has already been registered or in notifier's subdev list\n");
> +					"asd has already been registered or in notifier's subdev list\n");
>  				ret = -EEXIST;
>  				goto err_unlock;
>  			}

-- 
Kind regards,

Sakari Ailus
sakari.ailus@xxxxxxxxxxxxxxx



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