linux-kernel - RE: Linux Kernel handling AXI DECERR/SLVERR

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Message-ID: <BLUPR0201MB1505E332123C6483EB7D3D3EA50C0@BLUPR0201MB1505.namprd02.prod.outlook.com>
Date:   Wed, 20 Dec 2017 10:33:43 +0000
From:   Bharat Kumar Gogada <bharatku@...inx.com>
To:     Mark Rutland <mark.rutland@....com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        Will Deacon <Will.Deacon@....com>,
        "james.morse@....com" <james.morse@....com>,
        "julien.thierry@....com" <julien.thierry@....com>,
        "punit.agrawal@....com" <punit.agrawal@....com>,
        "tbaicar@...eaurora.org" <tbaicar@...eaurora.org>,
        "mingo@...nel.org" <mingo@...nel.org>
Subject: RE: Linux Kernel handling AXI DECERR/SLVERR

On Tue, Dec 19, 2017 at 11:28:49AM +0000, Bharat Kumar Gogada wrote:
> In our case the peripheral returns SLVERR first time and we see the following print but kernel do not hang.
> [  231.484186] Unhandled fault: synchronous external abort 
> (0x92000210) at 0x0000007f9241f880 Bus error
> 
> And from simulation we know that subsequent access to peripheral 
> returns OKAY response, however we see subsequent access fail with same 
> above bus error when we boot Linux.
> 
> Is there a way to handle these synchronous abort gracefully in Linux 
> or are these fatal ?

We don't currently have any mechanism to handle these, though it might be possible for synchronous abort.
Since currently there is no mechanism to handle, if once synchronous abort is received from a peripheral,
consecutive access will show up same error even peripheral responds with OKAY ?
What are the possible ways for handling these ?

Do you know why the device is returning SLVERR in this case?
There is an error being detected by the device.

Bharat