Re: [UNVERIFIED SENDER] Re: [PATCH v2 2/3] soc: amazon: al-pos: Introduce Amazon's Annapurna Labs POS driver

From: Shenhar, Talel
Date: Thu Sep 12 2019 - 02:50:35 EST

Hi Marc,

On 9/11/2019 5:15 PM, Marc Zyngier wrote:

Hi Talel,

On Tue, 10 Sep 2019 20:05:09 +0100,
Talel Shenhar <talel@xxxxxxxxxx> wrote:

+ log1 = readl(pos->mmio_base + AL_POS_ERROR_LOG_1);
Do you actually need the implied barriers? I'd expect that relaxed
accesses should be enough.

You are correct. Barriers are not needed, In v1 this driver indeed used _relaxed versions.

Due to request coming from Arnd in v1 patch series I removed it. As this is not data path I had no strong objection for removing it.

+ return IRQ_NONE;
+ log0 = readl(pos->mmio_base + AL_POS_ERROR_LOG_0);
+ writel(0, pos->mmio_base + AL_POS_ERROR_LOG_1);
+ addr |= (FIELD_GET(AL_POS_ERROR_LOG_1_ADDR_HIGH, log1) << 32);
+ request_id = FIELD_GET(AL_POS_ERROR_LOG_1_REQUEST_ID, log1);
+ bresp = FIELD_GET(AL_POS_ERROR_LOG_1_BRESP, log1);
+ dev_err(&pdev->dev, "addr=0x%llx request_id=0x%x bresp=0x%x\n",
+ addr, request_id, bresp);
What is this information? How do we make use of it? Given that this is
asynchronous, how do we correlate it to the offending software?

Indeed this information arriving from the HW is asynchronous.

There is no direct method to get the offending software.

There are all kinds of hacks we do to find the offending software once we find this error. most of the time its a new patch introduced but some of the time is just digging.

The whole think looks to me like a poor man's EDAC handling, and I'd
expect to be plugged in that subsystem instead. Any reason why this
isn't the case? It would certainly make the handling uniform for the

This logic was not plugged into EDAC as there is no "Correctable" error here. its just error event. Not all errors are EDAC in the sense of Error Detection And *Correction*. There are no correctable errors for this driver.

So plugging it under EDAC seems like abusing the EDAC system.

Now that I've emphasize the reason for not putting this under EDAC, what do you think? should this "only uncorrectable event" driver should be part of EDAC?