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

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Message-ID: <ea1a6672-0cbb-86b7-c8cd-0759edb94f85@arm.com>
Date:   Wed, 25 Jul 2018 10:01:53 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Rob Herring <robh@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
        Matt Sealey <matt.sealey@....com>,
        Charles Garcia-Tobin <charles.garcia-tobin@....com>,
        coresight@...ts.linaro.org, John Horley <john.horley@....com>,
        Mike Leach <mike.leach@...aro.org>
Subject: Re: [PATCH v2 02/10] coresight: platform: Refactor graph endpoint
 parsing

On 07/24/2018 10:34 PM, Mathieu Poirier wrote:
> On Tue, 24 Jul 2018 at 15:30, Mathieu Poirier
> <mathieu.poirier@...aro.org> 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@...aro.org>
>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
>>> ---
>>> 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.

Me neither..

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

Or may be we could do something with the return value :

	  1 - Successfully parsed and populated a connection entry
	  0 - No errors in parsing
	< 0 - Errors in parsing

>>> @@ -132,64 +184,33 @@ of_get_coresight_platform_data(struct device *dev,


>>> +     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.
>>                   */

Sure, will fix it.


Suzuki