linux-kernel - Re: [PATCH 0/2] Add iProc IDM device support

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Message-ID: <69ff3b8a-e99e-7128-a02a-1cac1da3eb66@broadcom.com>
Date:   Mon, 9 Dec 2019 16:19:02 -0800
From:   Ray Jui <ray.jui@...adcom.com>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        devicetree@...r.kernel.org,
        Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>,
        linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/2] Add iProc IDM device support



On 12/9/19 10:36 AM, Marc Zyngier wrote:
> On Mon, 9 Dec 2019 10:02:53 -0800
> Ray Jui <ray.jui@...adcom.com> wrote:
> 
>> On 12/7/19 9:39 AM, Marc Zyngier wrote:
>>> On Mon,  2 Dec 2019 15:31:25 -0800
>>> Ray Jui <ray.jui@...adcom.com> wrote:
>>>    
>>>> The Broadcom iProc IDM device allows control and monitoring of ASIC internal
>>>> bus transactions. Most importantly, it can be configured to detect bus
>>>> transaction timeout. In such case, critical information such as transaction
>>>> address that caused the error, bus master ID of the transaction that caused
>>>> the error, and etc., are made available from the IDM device.
>>>
>>> This seems to have many of the features of an EDAC device reporting
>>> uncorrectable errors.
>>>
>>> Is there any reason why it is not implemented as such?
>>>
>>> Thanks,
>>>
>>> 	M.
>>>    
>>
>> I thought EDAC errors (in fact, in our case, that's fatal rather than
>> uncorrectable) are mostly for DDR. Is my understanding incorrect?
> 
> No, they are for HW errors in general. There is no real limitation of
> scope, as far as I understand. Recently, the Annapurna guys came up
> with a similar HW block, and were convinced to make it an EDAC device.
> 
> See [1] for details.
> 
> Thanks,
> 
> 	M.
> 
> [1] https://lore.kernel.org/linux-devicetree/1570707681-865-1-git-send-email-talel@amazon.com/
> 

Ah I see. It looks like memory controllers are the primary devices 
supported by EDAC. In addition to that, EDAC also does seem to provide a 
generic data structure to support other types of HW devices and error 
events. I'll look into this and get back.

Thanks,

Ray