Re: [PATCH v2 02/10] coresight: platform: Refactor graph endpoint parsing

[Mathieu Poirier]

On Tue, 24 Jul 2018 at 15:30, Mathieu Poirier
<mathieu.poirier@xxxxxxxxxx> wrote:
>
> Good afternoon,
>
> On Thu, Jul 19, 2018 at 11:55:06AM +0100, Suzuki K Poulose wrote:
> > Refactor the of graph endpoint parsing code, to make the error
> > handling easier.
> >
> > Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > ---
> > Changes since v1:
> >  - Splitted from the of_node refcounting fix, part1
> > ---
> >  drivers/hwtracing/coresight/of_coresight.c | 129 +++++++++++++++++------------
> >  1 file changed, 75 insertions(+), 54 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/of_coresight.c b/drivers/hwtracing/coresight/of_coresight.c
> > index 6880bee..68faaf8 100644
> > --- a/drivers/hwtracing/coresight/of_coresight.c
> > +++ b/drivers/hwtracing/coresight/of_coresight.c
> > @@ -114,17 +114,69 @@ int of_coresight_get_cpu(const struct device_node *node)
> >  }
> >  EXPORT_SYMBOL_GPL(of_coresight_get_cpu);
> >
> > +/*
> > + * of_coresight_parse_endpoint : Parse the given output endpoint @ep
> > + * and fill the connection information in @pdata[*@i].
> > + *
> > + * Parses the local port, remote device name and the remote port. Also
> > + * updates *@i to point to the next index, when an entry is added.
> > + *
> > + * Returns :
> > + *    0      - If the parsing completed without any fatal errors.
> > + *   -Errno  - Fatal error, abort the scanning.
> > + */
> > +static int of_coresight_parse_endpoint(struct device *dev,
> > +                                    struct device_node *ep,
> > +                                    struct coresight_platform_data *pdata,
> > +                                    int *i)
> > +{
> > +     int ret = 0;
> > +     struct of_endpoint endpoint, rendpoint;
> > +     struct device_node *rparent = NULL;
> > +     struct device_node *rport = NULL;
> > +     struct device *rdev = NULL;
> > +
> > +     do {
> > +             /* Parse the local port details */
> > +             if (of_graph_parse_endpoint(ep, &endpoint))
> > +                     break;
> > +             /*
> > +              * Get a handle on the remote port and parent
> > +              * attached to it.
> > +              */
> > +             rparent = of_graph_get_remote_port_parent(ep);
> > +             if (!rparent)
> > +                     break;
> > +             rport = of_graph_get_remote_port(ep);
> > +             if (!rport)
> > +                     break;
> > +             if (of_graph_parse_endpoint(rport, &rendpoint))
> > +                     break;
> > +
> > +             /* If the remote device is not available, defer probing */
> > +             rdev = of_coresight_get_endpoint_device(rparent);
> > +             if (!rdev) {
> > +                     ret = -EPROBE_DEFER;
> > +                     break;
> > +             }
> > +
> > +             pdata->outports[*i] = endpoint.port;
> > +             pdata->child_names[*i] = dev_name(rdev);
> > +             pdata->child_ports[*i] = rendpoint.id;
> > +             /* Move the index */
> > +             (*i)++;
>
> Not a big fan, makes the code needlessly complex.  Incrementation of the index
> can be done in the while loop of of_get_coresight_platform_data().  See below.

Void that - it properly deals with the first of_parse_endpoint().

>
> > +     } while (0);
> > +
> > +     return ret;
> > +}
> > +
> >  struct coresight_platform_data *
> >  of_get_coresight_platform_data(struct device *dev,
> >                              const struct device_node *node)
> >  {
> >       int i = 0, ret = 0;
> >       struct coresight_platform_data *pdata;
> > -     struct of_endpoint endpoint, rendpoint;
> > -     struct device *rdev;
> >       struct device_node *ep = NULL;
> > -     struct device_node *rparent = NULL;
> > -     struct device_node *rport = NULL;
> >
> >       pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> >       if (!pdata)
> > @@ -132,64 +184,33 @@ of_get_coresight_platform_data(struct device *dev,
> >
> >       /* Use device name as sysfs handle */
> >       pdata->name = dev_name(dev);
> > +     pdata->cpu = of_coresight_get_cpu(node);
> >
> >       /* Get the number of input and output port for this component */
> >       of_coresight_get_ports(node, &pdata->nr_inport, &pdata->nr_outport);
> >
> > -     if (pdata->nr_outport) {
> > -             ret = of_coresight_alloc_memory(dev, pdata);
> > +     /* If there are no output connections, we are done */
> > +     if (!pdata->nr_outport)
> > +             return pdata;
> > +
> > +     ret = of_coresight_alloc_memory(dev, pdata);
> > +     if (ret)
> > +             return ERR_PTR(ret);
> > +
> > +     /* Iterate through each port to discover topology */
> > +     while ((ep = of_graph_get_next_endpoint(node, ep))) {
> > +             /*
> > +              * No need to deal with input ports, processing for as
> > +              * processing for output ports will deal with them.
> > +              */
>
> This comment has been broken for a while... It should read:
>
>                 /*
>                  * No need to deal with input ports, as processing
>                  * for output ports will deal with them.
>                  */
>
> > +             if (of_find_property(ep, "slave-mode", NULL))
> > +                     continue;
> > +
> > +             ret = of_coresight_parse_endpoint(dev, ep, pdata, &i);
> >               if (ret)
> >                       return ERR_PTR(ret);
>
>                 i++;
>
> > -
> > -             /* Iterate through each port to discover topology */
> > -             do {
> > -                     /* Get a handle on a port */
> > -                     ep = of_graph_get_next_endpoint(node, ep);
> > -                     if (!ep)
> > -                             break;
> > -
> > -                     /*
> > -                      * No need to deal with input ports, processing for as
> > -                      * processing for output ports will deal with them.
> > -                      */
> > -                     if (of_find_property(ep, "slave-mode", NULL))
> > -                             continue;
> > -
> > -                     /* Get a handle on the local endpoint */
> > -                     ret = of_graph_parse_endpoint(ep, &endpoint);
> > -
> > -                     if (ret)
> > -                             continue;
> > -
> > -                     /* The local out port number */
> > -                     pdata->outports[i] = endpoint.port;
> > -
> > -                     /*
> > -                      * Get a handle on the remote port and parent
> > -                      * attached to it.
> > -                      */
> > -                     rparent = of_graph_get_remote_port_parent(ep);
> > -                     rport = of_graph_get_remote_port(ep);
> > -
> > -                     if (!rparent || !rport)
> > -                             continue;
> > -
> > -                     if (of_graph_parse_endpoint(rport, &rendpoint))
> > -                             continue;
> > -
> > -                     rdev = of_coresight_get_endpoint_device(rparent);
> > -                     if (!rdev)
> > -                             return ERR_PTR(-EPROBE_DEFER);
> > -
> > -                     pdata->child_names[i] = dev_name(rdev);
> > -                     pdata->child_ports[i] = rendpoint.id;
> > -
> > -                     i++;
> > -             } while (ep);
> >       }
> >
> > -     pdata->cpu = of_coresight_get_cpu(node);
> > -
> >       return pdata;
> >  }
> >  EXPORT_SYMBOL_GPL(of_get_coresight_platform_data);
> > --
> > 2.7.4
> >