lkml.org 
[lkml]   [2022]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v4 1/7] device property: Helper to match multiple connections
    On Sun, Mar 06, 2022 at 07:40:34PM -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
    > Type-C connector. In this case the connector needs to belong to a graph
    > with multiple matching remote endpoints, and the Type-C controller needs
    > to be able to resolve them both.
    >
    > Add a new API that allows this kind of lookup.

    Thanks for the update!

    First of all, I have noticed that subject misses the verb, something like Add
    or Introduce.

    ...

    > +/**
    > + * 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

    (Optional) array...

    > + * @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 @matches is NULL @matches_len is ignored and the total number of resolved
    > + * matches is returned.

    I would require matches_len to be 0, see below.

    > + * Return: Number of matches resolved, or 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_graph;
    > + unsigned int count_ref;
    > +
    > + if (!fwnode || !match)
    > + return -EINVAL;
    > +
    > + count_graph = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
    > + matches, matches_len);

    > + if (matches) {
    > + matches += count_graph;
    > + matches_len -= count_graph;
    > + }

    So, the valid case is matches != NULL and matches_len == 0. For example, when
    we have run something previously on the buffer and it becomes full.

    In this case we have carefully handle this case.

    if (matches) {
    matches += count_graph;
    if (matches_len)
    matches_len -= count_graph;
    }

    Seems it can be also

    if (matches)
    matches += count_graph;

    if (matches_len)
    matches_len -= count_graph;

    That said, do we have a test cases for this?

    > + count_ref = fwnode_devcon_matches(fwnode, con_id, data, match,
    > + matches, matches_len);
    > +
    > + return count_graph + count_ref;
    > +}

    --
    With Best Regards,
    Andy Shevchenko


    \
     
     \ /
      Last update: 2022-03-07 11:47    [W:4.647 / U:0.112 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site