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Subject: Re: [PATCH v4 4/4] edac: Add support for Amazon's Annapurna Labs L2
 EDAC
To:     James Morse <james.morse@arm.com>
CC:     <robh+dt@kernel.org>, <mark.rutland@arm.com>, <bp@alien8.de>,
        <mchehab@kernel.org>, <davem@davemloft.net>,
        <gregkh@linuxfoundation.org>, <linus.walleij@linaro.org>,
        <Jonathan.Cameron@huawei.com>, <nicolas.ferre@microchip.com>,
        <paulmck@linux.ibm.com>, <dwmw@amazon.co.uk>, <benh@amazon.com>,
        <ronenk@amazon.com>, <talel@amazon.com>, <jonnyc@amazon.com>,
        <hanochu@amazon.com>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <linux-edac@vger.kernel.org>
References: <20190801130956.26388-1-hhhawa@amazon.com>
 <20190801130956.26388-5-hhhawa@amazon.com>
 <a060cbce-14f3-0592-4998-0a900d3fe6e4@arm.com>
From:   "Hawa, Hanna" <hhhawa@amazon.com>
Message-ID: <907e9e91-0830-7643-a329-8587541635da@amazon.com>
Date:   Mon, 5 Aug 2019 16:14:45 +0300
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On 8/2/2019 6:11 PM, James Morse wrote:
> Hi Hanna,
> 
> On 01/08/2019 14:09, Hanna Hawa wrote:
>> Adds support for Amazon's Annapurna Labs L2 EDAC driver to detect and
>> report L2 errors.
>> diff --git a/drivers/edac/al_l2_edac.c b/drivers/edac/al_l2_edac.c
>> new file mode 100644
>> index 000000000000..6c6d37cf82ab
>> --- /dev/null
>> +++ b/drivers/edac/al_l2_edac.c
>> @@ -0,0 +1,189 @@
> 
>> +#include <asm/sysreg.h>
>> +#include <linux/bitfield.h>
> 
> #include <linux/cpumask.h> ?

Will be added.

> 
>> +#include <linux/of.h>
>> +#include <linux/smp.h>
> 
> [...]
> 
>> +static void al_l2_edac_l2merrsr(void *arg)
>> +{
>> +	struct edac_device_ctl_info *edac_dev = arg;
>> +	int cpu, i;
>> +	u32 ramid, repeat, other, fatal;
>> +	u64 val = read_sysreg_s(ARM_CA57_L2MERRSR_EL1);
>> +	char msg[AL_L2_EDAC_MSG_MAX];
>> +	int space, count;
>> +	char *p;
>> +
>> +	if (!(FIELD_GET(ARM_CA57_L2MERRSR_VALID, val)))
>> +		return;
>> +
>> +	write_sysreg_s(0, ARM_CA57_L2MERRSR_EL1);
>> +
>> +	cpu = smp_processor_id();
>> +	ramid = FIELD_GET(ARM_CA57_L2MERRSR_RAMID, val);
>> +	repeat = FIELD_GET(ARM_CA57_L2MERRSR_REPEAT, val);
>> +	other = FIELD_GET(ARM_CA57_L2MERRSR_OTHER, val);
>> +	fatal = FIELD_GET(ARM_CA57_L2MERRSR_FATAL, val);
>> +
>> +	space = sizeof(msg);
>> +	p = msg;
>> +	count = scnprintf(p, space, "CPU%d L2 %serror detected", cpu,
>> +			  (fatal) ? "Fatal " : "");
>> +	p += count;
>> +	space -= count;
>> +
>> +	switch (ramid) {
>> +	case ARM_CA57_L2_TAG_RAM:
>> +		count = scnprintf(p, space, " RAMID='L2 Tag RAM'");
>> +		break;
>> +	case ARM_CA57_L2_DATA_RAM:
>> +		count = scnprintf(p, space, " RAMID='L2 Data RAM'");
>> +		break;
>> +	case ARM_CA57_L2_SNOOP_RAM:
>> +		count = scnprintf(p, space, " RAMID='L2 Snoop RAM'");
> 
> Nit: The TRMs both call this 'L2 Snoop Tag RAM'. Could we include 'tag' in the
> description. 'tag' implies its some kind of metadata, so an uncorrected error here affect
> a now unknown location, its more series than a 'data RAM' error. v8.2 would term this kind
> of error 'uncontained'.

Ack, will be fixed.

> 
> 
>> +		break;
>> +	case ARM_CA57_L2_DIRTY_RAM:
>> +		count = scnprintf(p, space, " RAMID='L2 Dirty RAM'");
>> +		break;
>> +	case ARM_CA57_L2_INC_PF_RAM:
>> +		count = scnprintf(p, space, " RAMID='L2 internal metadat'");
> 
> Nit: metadata

Ack, will be fixed.

> 
>> +		break;
>> +	default:
>> +		count = scnprintf(p, space, " RAMID='unknown'");
>> +		break;
>> +	}
>> +
>> +	p += count;
>> +	space -= count;
>> +
>> +	count = scnprintf(p, space,
>> +			  " repeat=%d, other=%d (L2MERRSR_EL1=0x%llx)",
>> +			  repeat, other, val);
>> +
>> +	for (i = 0; i < repeat; i++) {
>> +		if (fatal)
>> +			edac_device_handle_ue(edac_dev, 0, 0, msg);
>> +		else
>> +			edac_device_handle_ce(edac_dev, 0, 0, msg);
>> +	}
>> +}
> 
> [...]
> 
>> +static int al_l2_edac_probe(struct platform_device *pdev)
>> +{
>> +	struct edac_device_ctl_info *edac_dev;
>> +	struct al_l2_edac *al_l2;
>> +	struct device *dev = &pdev->dev;
>> +	int ret, i;
>> +
>> +	edac_dev = edac_device_alloc_ctl_info(sizeof(*al_l2),
>> +					      (char *)dev_name(dev), 1, "L", 1,
>> +					      2, NULL, 0,
>> +					      edac_device_alloc_index());
>> +	if (IS_ERR_OR_NULL(edac_dev))
>> +		return -ENOMEM;
>> +
>> +	al_l2 = edac_dev->pvt_info;
>> +	edac_dev->edac_check = al_l2_edac_check;
>> +	edac_dev->dev = dev;
>> +	edac_dev->mod_name = DRV_NAME;
>> +	edac_dev->dev_name = dev_name(dev);
>> +	edac_dev->ctl_name = "L2 cache";
>> +	platform_set_drvdata(pdev, edac_dev);
> 
>> +	for_each_online_cpu(i) {
> 
> for_each_possible_cpu()?
> 
> If you boot with maxcpus= the driver's behaviour changes.
> But you are only parsing information from the DT, so you don't really need the CPUs to be
> online.
Agree, for dt parsing no need the online CPUs, if 
for_each_possible_cpu() used then smp_call_function_any() will run only 
on the online CPUs in the mask.

Will change to for_each_possible_cpu().

> 
> 
>> +		struct device_node *cpu;
>> +		struct device_node *cpu_cache, *l2_cache;
>> +
>> +		cpu = of_get_cpu_node(i, NULL);
> 
> (of_get_cpu_node() can return NULL, but I don't think it can ever happen like this)
> 
>> +		cpu_cache = of_find_next_cache_node(cpu);
>> +		l2_cache = of_parse_phandle(dev->of_node, "l2-cache", 0);
>> +
>> +		if (cpu_cache == l2_cache)
>> +			cpumask_set_cpu(i, &al_l2->cluster_cpus);
> 
> You need to of_node_put() these device_node pointers once you're done with them.

Will be added.

> 
> 
>> +	}
>> +
>> +	if (cpumask_empty(&al_l2->cluster_cpus)) {
>> +		dev_err(dev, "CPU mask is empty for this L2 cache\n");
>> +		ret = -EINVAL;
>> +		goto err;
>> +	}
>> +
>> +	ret = edac_device_add_device(edac_dev);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to add L2 edac device\n");
>> +		goto err;
>> +	}
>> +
>> +	return 0;
>> +
>> +err:
>> +	edac_device_free_ctl_info(edac_dev);
>> +
>> +	return ret;
>> +}
> 
> With the of_node_put()ing:
> Reviewed-by: James Morse <james.morse@arm.com>

Thanks for review, will publish v5 with the above fixes.

Thanks,
Hanna

> 
> 
> Thanks,
> 
> James
>