linux-kernel - Re: [RFC PATCH] coresight: dynamic-replicator: Fix handling of multiple connections

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <526ee10ba1df05b41f9471613550a0fd@codeaurora.org>
Date:   Thu, 23 Apr 2020 17:51:40 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     mike.leach@...aro.org, mathieu.poirier@...aro.org,
        leo.yan@...aro.org, alexander.shishkin@...ux.intel.com,
        swboyd@...omium.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [RFC PATCH] coresight: dynamic-replicator: Fix handling of
 multiple connections

Hi Suzuki,

On 2020-04-07 20:23, Suzuki K Poulose wrote:
> On 04/07/2020 02:56 PM, Sai Prakash Ranjan wrote:
>> Hi Suzuki,
>> 
>> On 2020-04-07 18:38, Suzuki K Poulose wrote:
>>> On 04/07/2020 12:29 PM, Sai Prakash Ranjan wrote:
>>>> Hi Suzuki,
>>>> 
>>>> Thanks for looking into this issue.
>>>> 
>>>> On 2020-04-07 15:54, Suzuki K Poulose wrote:
>>>>> On 04/07/2020 10:46 AM, Sai Prakash Ranjan wrote:
>>>>> 
>>>>> There seems to be two replicators back to back here. What is 
>>>>> connected
>>>>> to the other output of both of them ? Are there any TPIUs ? What 
>>>>> happens
>>>>> if you choose a sink on the other end of "swao_replicator" (ETB ?)
>>>>> 
>>>> 
>>>> The other outport of swao replicator is connected to EUD which is a
>>>> QCOM specific HW which can be used as a sink like USB.
>>>> And the other outport of other replicator(replicator_out) is 
>>>> connected to
>>>> TPIU.
>>>> 
>>>>> After boot, what do the idfilter registers read for both the 
>>>>> replicators ?
>>>>> 
>>>> 
>>>> Added some prints in replicator_probe.
>>>> 
>>>>   replicator probe ret=-517 devname=6046000.replicator idfilter0=0x0 
>>>> idfilter1=0x0
>>>>   replicator probe ret=0 devname=6b06000.replicator idfilter0=0xff 
>>>> idfilter1=0xff
>>>>   replicator probe ret=0 devname=6046000.replicator idfilter0=0xff 
>>>> idfilter1=0xff
>>> 
>>> Curious to see how the idfilterX is set to 0:
>>>      if that is never used.
>>>         Or
>>>      if the user doesn't reset it back to 0xff.
>>> 
>> 
>> For both replicators, the default value seems to be 0x0.
>> 
>>   replicator probe in res ret=0 devname=6046000.replicator 
>> idfilter0=0x0 idfilter1=0x0
>>   replicator probe ret=-517 devname=6046000.replicator idfilter0=0x0 
>> idfilter1=0x0
>>   replicator probe in res ret=0 devname=6b06000.replicator 
>> idfilter0=0x0 idfilter1=0x0
>>   replicator probe ret=0 devname=6b06000.replicator idfilter0=0xff 
>> idfilter1=0xff
>>   replicator probe in res ret=0 devname=6046000.replicator 
>> idfilter0=0x0 idfilter1=0x0
>>   replicator probe ret=0 devname=6046000.replicator idfilter0=0xff 
>> idfilter1=0xff
> 
> I am not sure how you have added the debugs, but it looks like the
> drivers set 0xff for both the port filters on a successful probe.
> 

About the earlier mentioned points on:

1) Disallow turning the replicator ON, when it is already turned ON
2) Do what your patch does. i.e, disable the other end while one end
    is turned on.

Do we need 1) and should we go ahead with this?

Thanks,
Sai

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a 
member
of Code Aurora Forum, hosted by The Linux Foundation