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    SubjectRe: [PATCH 3/8] device property: Helper to match multiple connections
    Hi Björn,

    (And thanks to Heikki for cc'ing me!)

    On Thu, Dec 30, 2021 at 11:26:34AM +0200, Heikki Krogerus wrote:
    > +Andy, Dan and Sakari
    >
    > On Mon, Dec 27, 2021 at 09:21:11PM -0800, Bjorn Andersson wrote:
    > > In some cases multiple connections with the same connection id
    > > needs to be resolved from a fwnode graph.
    > >
    > > One such example is when separate hardware is used for performing muxing and/or
    > > orientation switching of the SuperSpeed and SBU lines in a USB-C
    > > connector. In this case the connector needs to belong to a graph with
    > > multiple matching remote endpoints, and the TypeC controller needs to be
    > > able to resolve them both.
    > >
    > > Add a new API that allows this kind of lookup.
    > >
    > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
    > > ---
    > > drivers/base/property.c | 94 ++++++++++++++++++++++++++++++++++++++++
    > > include/linux/property.h | 5 +++
    > > 2 files changed, 99 insertions(+)
    > >
    > > diff --git a/drivers/base/property.c b/drivers/base/property.c
    > > index cbe4fa298413..0aa0296fd991 100644
    > > --- a/drivers/base/property.c
    > > +++ b/drivers/base/property.c
    > > @@ -1180,6 +1180,36 @@ fwnode_graph_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
    > > return NULL;
    > > }
    > >
    > > +static unsigned int fwnode_graph_devcon_matches(struct fwnode_handle *fwnode,
    > > + const char *con_id, void *data,
    > > + devcon_match_fn_t match,
    > > + void **matches,
    > > + unsigned int matches_len)
    > > +{
    > > + struct fwnode_handle *node;
    > > + struct fwnode_handle *ep;
    > > + unsigned int count = 0;
    > > + void *ret;
    > > +
    > > + fwnode_graph_for_each_endpoint(fwnode, ep) {
    > > + if (count >= matches_len) {
    > > + fwnode_handle_put(ep);
    > > + return count;
    > > + }
    > > +
    > > + node = fwnode_graph_get_remote_port_parent(ep);
    > > + if (!fwnode_device_is_available(node))

    The reference to node needs to be put here.

    > > + continue;
    > > +
    > > + ret = match(node, con_id, data);
    > > + fwnode_handle_put(node);
    > > +
    > > + if (ret)
    > > + matches[count++] = ret;
    > > + }
    > > + return count;
    > > +}
    > > +
    > > static void *
    > > fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
    > > void *data, devcon_match_fn_t match)
    > > @@ -1202,6 +1232,35 @@ fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
    > > return NULL;
    > > }
    > >
    > > +static unsigned int fwnode_devcon_matches(struct fwnode_handle *fwnode,
    > > + const char *con_id, void *data,
    > > + devcon_match_fn_t match,
    > > + void **matches,
    > > + unsigned int matches_len)
    > > +{
    > > + struct fwnode_handle *node;
    > > + unsigned int count = 0;
    > > + void *ret;
    > > + int i;

    unsigned int, please.

    > > +
    > > + for (i = 0; ; i++) {
    > > + if (count >= matches_len)
    > > + return count;
    > > +
    > > + node = fwnode_find_reference(fwnode, con_id, i);
    > > + if (IS_ERR(node))
    > > + break;
    > > +
    > > + ret = match(node, NULL, data);
    > > + fwnode_handle_put(node);
    > > +
    > > + if (ret)
    > > + matches[count++] = ret;
    > > + }
    > > +
    > > + return count;
    > > +}
    > > +
    > > /**
    > > * fwnode_connection_find_match - Find connection from a device node
    > > * @fwnode: Device node with the connection
    > > @@ -1229,3 +1288,38 @@ void *fwnode_connection_find_match(struct fwnode_handle *fwnode,
    > > return fwnode_devcon_match(fwnode, con_id, data, match);
    > > }
    > > EXPORT_SYMBOL_GPL(fwnode_connection_find_match);
    > > +
    > > +/**
    > > + * fwnode_connection_find_matches - Find connections from a device node
    > > + * @fwnode: Device node with the connection
    > > + * @con_id: Identifier for the connection
    > > + * @data: Data for the match function
    > > + * @match: Function to check and convert the connection description
    > > + * @matches: Array of pointers to fill with matches
    > > + * @matches_len: Length of @matches
    > > + *
    > > + * Find up to @matches_len connections with unique identifier @con_id between
    > > + * @fwnode and other device nodes. @match will be used to convert the
    > > + * connection description to data the caller is expecting to be returned
    > > + * through the @matches array.

    If the caller allocates the matches array, how does it know how large it
    should be? Is there a need to provide a way to count the matches before
    writing them to an array? Most similar functions do that by just setting the
    array (matches) to NULL.

    > > + *
    > > + * Return: Number of matches resolved, of negative errno.
    > > + */
    > > +int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
    > > + const char *con_id, void *data,
    > > + devcon_match_fn_t match,
    > > + void **matches, unsigned int matches_len)
    > > +{
    > > + unsigned int count;
    > > +
    > > + if (!fwnode || !match || !matches)
    > > + return -EINVAL;
    > > +
    > > + count = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
    > > + matches, matches_len);
    > > +
    > > + return count + fwnode_devcon_matches(fwnode, con_id, data, match,
    > > + matches + count,
    > > + matches_len - count);
    > > +}
    > > +EXPORT_SYMBOL_GPL(fwnode_connection_find_matches);
    > > diff --git a/include/linux/property.h b/include/linux/property.h
    > > index 16f736c698a2..59484ccb260e 100644
    > > --- a/include/linux/property.h
    > > +++ b/include/linux/property.h
    > > @@ -444,6 +444,11 @@ static inline void *device_connection_find_match(struct device *dev,
    > > return fwnode_connection_find_match(dev_fwnode(dev), con_id, data, match);
    > > }
    > >
    > > +int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
    > > + const char *con_id, void *data,
    > > + devcon_match_fn_t match,
    > > + void **matches, unsigned int matches_len);
    > > +
    > > /* -------------------------------------------------------------------------- */
    > > /* Software fwnode support - when HW description is incomplete or missing */
    > >

    --
    Kind regards,

    Sakari Ailus

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