linux-kernel - Re: [RFC PATCH 2/8] coresight: Fix remote endpoint parsing

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Message-ID: <005ec90b-6697-1b33-de01-b5f2a6c509cf@arm.com>
Date:   Mon, 4 Jun 2018 11:34:32 +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>,
        Sudeep Holla <sudeep.holla@....com>,
        Rob Herring <robh@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Frank Rowand <frowand.list@...il.com>,
        Matt Sealey <matt.sealey@....com>,
        Charles Garcia-Tobin <charles.garcia-tobin@....com>,
        John Horley <john.horley@....com>,
        Mike Leach <mike.leach@...aro.org>, coresight@...ts.linaro.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org
Subject: Re: [RFC PATCH 2/8] coresight: Fix remote endpoint parsing

On 06/01/2018 08:46 PM, Mathieu Poirier wrote:
> On 1 June 2018 at 13:38, Mathieu Poirier <mathieu.poirier@...aro.org> wrote:
>> On Fri, Jun 01, 2018 at 02:16:01PM +0100, Suzuki K Poulose wrote:
>>> When parsing the remote endpoint of an output port, we do :
>>>       rport = of_graph_get_remote_port(ep);
>>>       rparent = of_graph_get_remote_port_parent(ep);
>>>
>>> and then parse the "remote_port" as if it was the remote endpoint,
>>> which is wrong. The code worked fine because we used endpoint number
>>> as the port number. Let us fix it and optimise a bit as:
>>>
>>>       remote_ep = of_graph_get_remote_endpoint(ep);
>>>       if (remote_ep)
>>>          remote_parent = of_graph_get_port_parent(remote_ep);
>>>
>>> and then, parse the remote_ep for the port/endpoint details.
>>>
>>> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
>>> ---
>>>   drivers/hwtracing/coresight/of_coresight.c | 19 ++++++++++---------
>>>   1 file changed, 10 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/of_coresight.c b/drivers/hwtracing/coresight/of_coresight.c
>>> index 7c37544..e0deab0 100644
>>> --- a/drivers/hwtracing/coresight/of_coresight.c
>>> +++ b/drivers/hwtracing/coresight/of_coresight.c
>>> @@ -128,7 +128,7 @@ of_get_coresight_platform_data(struct device *dev,
>>>        struct device *rdev;
>>>        struct device_node *ep = NULL;
>>>        struct device_node *rparent = NULL;
>>> -     struct device_node *rport = NULL;
>>> +     struct device_node *rep = NULL;
>>>
>>>        pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
>>>        if (!pdata)
>>> @@ -169,16 +169,17 @@ of_get_coresight_platform_data(struct device *dev,
>>>                        pdata->outports[i] = endpoint.port;
>>>
>>>                        /*
>>> -                      * Get a handle on the remote port and parent
>>> -                      * attached to it.
>>> +                      * Get a handle on the remote endpoint and the device
>>> +                      * it is attached to.
>>>                         */
>>> -                     rparent = of_graph_get_remote_port_parent(ep);
>>> -                     rport = of_graph_get_remote_port(ep);
>>> -
>>> -                     if (!rparent || !rport)
>>> +                     rep = of_graph_get_remote_endpoint(ep);
>>> +                     if (!rep)
>>> +                             continue;
>>> +                     rparent = of_graph_get_port_parent(rep);
>>> +                     if (!rparent)
>>>                                continue;
>>>
>>> -                     if (of_graph_parse_endpoint(rport, &rendpoint))
>>> +                     if (of_graph_parse_endpoint(rep, &rendpoint))
>>>                                continue;
>>
>> You are correct and I'm out to lunch.
>>
>>>
>>>                        rdev = of_coresight_get_endpoint_device(rparent);
>>> @@ -186,7 +187,7 @@ of_get_coresight_platform_data(struct device *dev,
>>>                                return ERR_PTR(-EPROBE_DEFER);
>>>
>>>                        pdata->child_names[i] = dev_name(rdev);
>>> -                     pdata->child_ports[i] = rendpoint.id;
>>> +                     pdata->child_ports[i] = rendpoint.port;
>>
>> You need to do a of_node_put() here for both rep and rparent.
> 
> Same thing for the "continue" and error condition above.


Mathieu,

Thanks for pointing that out. I see that we were missing them for the
existing code as well. I will clean all this up.

Cheers
Suzuki