linux-kernel - Re: [PATCH V23 2/3] misc: dcc: Add driver support for Data Capture and Compare unit(DCC)

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Date:   Wed, 31 May 2023 09:17:45 -0700
From:   Trilok Soni <quic_tsoni@...cinc.com>
To:     Souradeep Chowdhury <quic_schowdhu@...cinc.com>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, Alex Elder <elder@...e.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, Sibi Sankar <quic_sibis@...cinc.com>,
        Rajendra Nayak <quic_rjendra@...cinc.com>
Subject: Re: [PATCH V23 2/3] misc: dcc: Add driver support for Data Capture
 and Compare unit(DCC)

On 5/23/2023 10:10 PM, Trilok Soni wrote:
> On 5/4/2023 11:36 PM, Souradeep Chowdhury wrote:
>> The DCC is a DMA Engine designed to capture and store data during system
>> crash or software triggers. The DCC operates based on user inputs via
>> the debugfs interface. The user gives addresses as inputs and these
>> addresses are stored in the dcc sram. In case of a system crash or a
>> manual software trigger by the user through the debugfs interface, the
>> dcc captures and stores the values at these addresses. This patch
>> contains the driver which has all the methods pertaining to the debugfs
>> interface, auxiliary functions to support all the four fundamental
>> operations of dcc namely read, write, read/modify/write and loop. The
>> probe method here instantiates all the resources necessary for dcc to
>> operate mainly the dedicated dcc sram where it stores the values. The
>> DCC driver can be used for debugging purposes without going for a reboot
>> since it can perform software triggers as well based on user inputs.
>>
>> Also update the documentation for debugfs entries which explains the
>> functionalities of each debugfs file that has been created for dcc.
>> Update the documentation to reflect new module name for dcc.
>>
>> The following is the justification of using debugfs interface over the
>> other alternatives like sysfs/ioctls
>>
>> i) As can be seen from the debugfs attribute descriptions, some of the
>> debugfs attribute files here contains multiple arguments which needs to
>> be accepted from the user. This goes against the design style of sysfs.
>>
>> ii) The user input patterns have been made simple and convenient in this
>> case with the use of debugfs interface as user doesn't need to shuffle
>> between different files to execute one instruction as was the case on
>> using other alternatives.
>>
>> Signed-off-by: Souradeep Chowdhury <quic_schowdhu@...cinc.com>
>> Reviewed-by: Alex Elder <elder@...aro.org>
> 
> 
> Bjorn, do you have any remaining comments here? Are you going to provide 
>   your Reviewed-by here and other patches?
> 
> If there are no comments then I would like this series to be picked by 
> the maintainer you suggest.
> 

Gentle reminder again here. I would like to make some progress on DCC 
discussion here. Is it ready to be picked up by Bjorn or Arnd?

---Trilok Soni