Hi Hans,
On Mon, Sep 04, 2017 at 03:19:10PM +0200, Hans Verkuil wrote:
> On 09/03/2017 07:49 PM, Sakari Ailus wrote:
> > The current practice is that drivers iterate over their endpoints and
> > parse each endpoint separately. This is very similar in a number of
> > drivers, implement a generic function for the job. Driver specific matters
> > can be taken into account in the driver specific callback.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > ---
> > drivers/media/v4l2-core/v4l2-async.c | 16 ++++
> > drivers/media/v4l2-core/v4l2-fwnode.c | 136 ++++++++++++++++++++++++++++++++++
> > include/media/v4l2-async.h | 24 +++++-
> > include/media/v4l2-fwnode.h | 53 +++++++++++++
> > 4 files changed, 227 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > index 851f128eba22..6740a241d4a1 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -22,6 +22,7 @@
> >
> > #include <media/v4l2-async.h>
> > #include <media/v4l2-device.h>
> > +#include <media/v4l2-fwnode.h>
> > #include <media/v4l2-subdev.h>
> >
> > static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
> > @@ -278,6 +279,21 @@ void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> > }
> > EXPORT_SYMBOL(v4l2_async_notifier_unregister);
> >
> > +void v4l2_async_notifier_release(struct v4l2_async_notifier *notifier)
> > +{
> > + unsigned int i;
> > +
> > + for (i = 0; i < notifier->num_subdevs; i++)
> > + kfree(notifier->subdevs[i]);
> > +
> > + notifier->max_subdevs = 0;
> > + notifier->num_subdevs = 0;
> > +
> > + kvfree(notifier->subdevs);
> > + notifier->subdevs = NULL;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_async_notifier_release);
> > +
> > int v4l2_async_register_subdev(struct v4l2_subdev *sd)
> > {
> > struct v4l2_async_notifier *notifier;
> > diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
> > index 706f9e7b90f1..f8c7a9bc6a58 100644
> > --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> > +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> > @@ -19,6 +19,7 @@
> > */
> > #include <linux/acpi.h>
> > #include <linux/kernel.h>
> > +#include <linux/mm.h>
> > #include <linux/module.h>
> > #include <linux/of.h>
> > #include <linux/property.h>
> > @@ -26,6 +27,7 @@
> > #include <linux/string.h>
> > #include <linux/types.h>
> >
> > +#include <media/v4l2-async.h>
> > #include <media/v4l2-fwnode.h>
> >
> > enum v4l2_fwnode_bus_type {
> > @@ -313,6 +315,140 @@ void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link)
> > }
> > EXPORT_SYMBOL_GPL(v4l2_fwnode_put_link);
> >
> > +static int v4l2_async_notifier_realloc(struct v4l2_async_notifier *notifier,
> > + unsigned int max_subdevs)
> > +{
> > + struct v4l2_async_subdev **subdevs;
> > +
> > + if (max_subdevs <= notifier->max_subdevs)
> > + return 0;
> > +
> > + subdevs = kvmalloc_array(
> > + max_subdevs, sizeof(*notifier->subdevs),
> > + GFP_KERNEL | __GFP_ZERO);
> > + if (!subdevs)
> > + return -ENOMEM;
> > +
> > + if (notifier->subdevs) {
> > + memcpy(subdevs, notifier->subdevs,
> > + sizeof(*subdevs) * notifier->num_subdevs);
> > +
> > + kvfree(notifier->subdevs);
> > + }
> > +
> > + notifier->subdevs = subdevs;
> > + notifier->max_subdevs = max_subdevs;
> > +
> > + return 0;
> > +}
> > +
> > +static int v4l2_async_notifier_fwnode_parse_endpoint(
> > + struct device *dev, struct v4l2_async_notifier *notifier,
> > + struct fwnode_handle *endpoint, unsigned int asd_struct_size,
> > + int (*parse_endpoint)(struct device *dev,
> > + struct v4l2_fwnode_endpoint *vep,
> > + struct v4l2_async_subdev *asd))
> > +{
> > + struct v4l2_async_subdev *asd;
> > + struct v4l2_fwnode_endpoint *vep;
> > + int ret = 0;
> > +
> > + asd = kzalloc(asd_struct_size, GFP_KERNEL);
> > + if (!asd)
> > + return -ENOMEM;
> > +
> > + asd->match.fwnode.fwnode =
> > + fwnode_graph_get_remote_port_parent(endpoint);
> > + if (!asd->match.fwnode.fwnode) {
> > + dev_warn(dev, "bad remote port parent\n");
> > + ret = -EINVAL;
> > + goto out_err;
> > + }
> > +
> > + /* Ignore endpoints the parsing of which failed. */
> > + vep = v4l2_fwnode_endpoint_alloc_parse(endpoint);
> > + if (IS_ERR(vep)) {
> > + ret = PTR_ERR(vep);
> > + dev_warn(dev, "unable to parse V4L2 fwnode endpoint (%d)\n",
> > + ret);
> > + goto out_err;
> > + }
> > +
> > + ret = parse_endpoint ? parse_endpoint(dev, vep, asd) : 0;
>
> How likely is it that parse_endpoint will be NULL? I ask because if it is
> common, then you could put everything from v4l2_fwnode_endpoint_alloc_parse
> until just before 'asd->match_type = V4L2_ASYNC_MATCH_FWNODE;' under
> 'if (parse_endpoint) {'.
>
> The disadvantage is that you won't see parse errors, but on the other hand
> nobody apparently needs it, so why bother. I'm not sure what is the right thing
> to do here.
If a driver later on is amended with that parse_endpoint callback for a
reason or another, then a range of boards could suddenly stop working. I'd
keep it for validation purposes at least.
I can't think this could ever a performance concern.
>
> > + v4l2_fwnode_endpoint_free(vep);
>
> Here vep is freed,
Oops. I still thought it actually did release only the variable length
fields. Of course it no longer did. Will fix.
>
> > + if (ret == -ENOTCONN) {
> > + dev_dbg(dev, "ignoring endpoint %u,%u\n", vep->base.port,
> > + vep->base.id);
>
> but still used here
>
> > + kfree(asd);
> > + return 0;
> > + } else if (ret < 0) {
> > + dev_warn(dev, "driver could not parse endpoint %u,%u (%d)\n",
> > + vep->base.port, vep->base.id, ret);
>
> and here.
>
> > + goto out_err;
> > + }
> > +
> > + asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
> > + notifier->subdevs[notifier->num_subdevs] = asd;
> > + notifier->num_subdevs++;
> > +
> > + return 0;
> > +
> > +out_err:
> > + fwnode_handle_put(asd->match.fwnode.fwnode);
> > + kfree(asd);
> > +
> > + return ret;
> > +}
> > +
> > +int v4l2_async_notifier_parse_fwnode_endpoints(
> > + struct device *dev, struct v4l2_async_notifier *notifier,
> > + size_t asd_struct_size,
> > + int (*parse_endpoint)(struct device *dev,
> > + struct v4l2_fwnode_endpoint *vep,
> > + struct v4l2_async_subdev *asd))
> > +{
> > + struct fwnode_handle *fwnode = NULL;
> > + unsigned int max_subdevs = notifier->max_subdevs;
> > + int ret;
> > +
> > + if (asd_struct_size < sizeof(struct v4l2_async_subdev))
> > + return -EINVAL;
> > +
> > + for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> > + dev_fwnode(dev), fwnode)); )
> > + if (fwnode_device_is_available(
> > + fwnode_graph_get_port_parent(fwnode)))
> > + max_subdevs++;
> > +
> > + /* No subdevs to add? Return here. */
> > + if (max_subdevs == notifier->max_subdevs)
> > + return 0;
> > +
> > + ret = v4l2_async_notifier_realloc(notifier, max_subdevs);
> > + if (ret)
> > + return ret;
> > +
> > + for (fwnode = NULL; (fwnode = fwnode_graph_get_next_endpoint(
> > + dev_fwnode(dev), fwnode)); ) {
> > + if (!fwnode_device_is_available(
> > + fwnode_graph_get_port_parent(fwnode)))
> > + continue;
> > +
> > + if (WARN_ON(notifier->num_subdevs >= notifier->max_subdevs))
> > + break;
>
> I think you should return an error here. I feel that if this happens, then
> something very strange is going on and you are better off returning -EINVAL
> or something like that.
Yeah, I'll change it.
>
> > +
> > + ret = v4l2_async_notifier_fwnode_parse_endpoint(
> > + dev, notifier, fwnode, asd_struct_size, parse_endpoint);
> > + if (ret < 0)
> > + break;
> > + }
> > +
> > + fwnode_handle_put(fwnode);
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_async_notifier_parse_fwnode_endpoints);
> > +
> > MODULE_LICENSE("GPL");
> > MODULE_AUTHOR("Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>");
> > MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>");
> > diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> > index c69d8c8a66d0..96fa1afc00dd 100644
> > --- a/include/media/v4l2-async.h
> > +++ b/include/media/v4l2-async.h
> > @@ -18,7 +18,6 @@ struct device;
> > struct device_node;
> > struct v4l2_device;
> > struct v4l2_subdev;
> > -struct v4l2_async_notifier;
> >
> > /* A random max subdevice number, used to allocate an array on stack */
> > #define V4L2_MAX_SUBDEVS 128U
> > @@ -50,6 +49,10 @@ enum v4l2_async_match_type {
> > * @match: union of per-bus type matching data sets
> > * @list: used to link struct v4l2_async_subdev objects, waiting to be
> > * probed, to a notifier->waiting list
> > + *
> > + * When this struct is used as a member in a driver specific struct,
> > + * the driver specific struct shall contain the @struct
> > + * v4l2_async_subdev as its first member.
> > */
> > struct v4l2_async_subdev {
> > enum v4l2_async_match_type match_type;
> > @@ -78,7 +81,8 @@ struct v4l2_async_subdev {
> > /**
> > * struct v4l2_async_notifier - v4l2_device notifier data
> > *
> > - * @num_subdevs: number of subdevices
> > + * @num_subdevs: number of subdevices used in the subdevs array
> > + * @max_subdevs: number of subdevices allocated in the subdevs array
> > * @subdevs: array of pointers to subdevice descriptors
> > * @v4l2_dev: pointer to struct v4l2_device
> > * @waiting: list of struct v4l2_async_subdev, waiting for their drivers
> > @@ -90,6 +94,7 @@ struct v4l2_async_subdev {
> > */
> > struct v4l2_async_notifier {
> > unsigned int num_subdevs;
> > + unsigned int max_subdevs;
> > struct v4l2_async_subdev **subdevs;
> > struct v4l2_device *v4l2_dev;
> > struct list_head waiting;
> > @@ -121,6 +126,21 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> > void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier);
> >
> > /**
> > + * v4l2_async_notifier_release - release notifier resources
> > + * @notifier: the notifier the resources of which are to be released
> > + *
> > + * Release memory resources related to a notifier, including the async
> > + * sub-devices allocated for the purposes of the notifier. The user is
> > + * responsible for releasing the notifier's resources after calling
> > + * @v4l2_async_notifier_parse_fwnode_endpoints.
> > + *
> > + * There is no harm from calling v4l2_async_notifier_release in other
> > + * cases as long as its memory has been zeroed after it has been
> > + * allocated.
> > + */
> > +void v4l2_async_notifier_release(struct v4l2_async_notifier *notifier);
> > +
> > +/**
> > * v4l2_async_register_subdev - registers a sub-device to the asynchronous
> > * subdevice framework
> > *
> > diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> > index 68eb22ba571b..6d125f26ec84 100644
> > --- a/include/media/v4l2-fwnode.h
> > +++ b/include/media/v4l2-fwnode.h
> > @@ -25,6 +25,8 @@
> > #include <media/v4l2-mediabus.h>
> >
> > struct fwnode_handle;
> > +struct v4l2_async_notifier;
> > +struct v4l2_async_subdev;
> >
> > #define V4L2_FWNODE_CSI2_MAX_DATA_LANES 4
> >
> > @@ -201,4 +203,55 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
> > */
> > void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
> >
> > +/**
> > + * v4l2_async_notifier_parse_fwnode_endpoints - Parse V4L2 fwnode endpoints in a
> > + * device node
> > + * @dev: the device the endpoints of which are to be parsed
> > + * @notifier: notifier for @dev
> > + * @asd_struct_size: size of the driver's async sub-device struct, including
> > + * sizeof(struct v4l2_async_subdev). The &struct
> > + * v4l2_async_subdev shall be the first member of
> > + * the driver's async sub-device struct, i.e. both
> > + * begin at the same memory address.
> > + * @parse_endpoint: Driver's callback function called on each V4L2 fwnode
> > + * endpoint. Optional.
> > + * Return: %0 on success
> > + * %-ENOTCONN if the endpoint is to be skipped but this
> > + * should not be considered as an error
> > + * %-EINVAL if the endpoint configuration is invalid
> > + *
> > + * Parse the fwnode endpoints of the @dev device and populate the async sub-
> > + * devices array of the notifier. The @parse_endpoint callback function is
> > + * called for each endpoint with the corresponding async sub-device pointer to
> > + * let the caller initialize the driver-specific part of the async sub-device
> > + * structure.
> > + *
> > + * The notifier memory shall be zeroed before this function is called on the
> > + * notifier.
> > + *
> > + * This function may not be called on a registered notifier and may be called on
> > + * a notifier only once. When using this function, the user may not access the
> > + * notifier's subdevs array nor change notifier's num_subdevs field, these are
> > + * reserved for the framework's internal use only.
>
> I don't think the sentence "When using...only" makes any sense. How would you
> even be able to access any of the notifier fields? You don't have access to it
> from the parse_endpoint callback.
Not from the parse_endpoint callback. The notifier is first set up by the
driver, and this text applies to that --- whether or not parse_endpoint is
given.
>
> I think it can just be dropped.
>
> > + *
> > + * The @struct v4l2_fwnode_endpoint passed to the callback function
> > + * @parse_endpoint is released once the function is finished. If there is a need
> > + * to retain that configuration, the user needs to allocate memory for it.
> > + *
> > + * Any notifier populated using this function must be released with a call to
> > + * v4l2_async_notifier_release() after it has been unregistered and the async
> > + * sub-devices are no longer in use.
> > + *
> > + * Return: %0 on success, including when no async sub-devices are found
> > + * %-ENOMEM if memory allocation failed
> > + * %-EINVAL if graph or endpoint parsing failed
> > + * Other error codes as returned by @parse_endpoint
> > + */
> > +int v4l2_async_notifier_parse_fwnode_endpoints(
> > + struct device *dev, struct v4l2_async_notifier *notifier,
> > + size_t asd_struct_size,
> > + int (*parse_endpoint)(struct device *dev,
> > + struct v4l2_fwnode_endpoint *vep,
> > + struct v4l2_async_subdev *asd));
> > +
> > #endif /* _V4L2_FWNODE_H */
> >
--
Regards,
Sakari Ailus
e-mail: sakari.ailus@xxxxxx
