Re: [PATCH v7 1/3] edac: Add support for Amazon's Annapurna Labs L1 EDAC

[Hawa, Hanna]

On 1/15/2020 8:49 PM, James Morse wrote:
> Hi Hanna,
>
> (This was still on my list. I've not seen a newer version, its not in next, and it still
> applies, so:)

Thank you.

> On 15/10/2019 13:09, Hanna Hawa wrote:
> > Adds support for Amazon's Annapurna Labs L1 EDAC driver to detect and
> > report L1 errors.
>
> > diff --git a/drivers/edac/al_l1_edac.c b/drivers/edac/al_l1_edac.c
> > new file mode 100644
> > index 000000000000..e363a80b4d13
> > --- /dev/null
> > +++ b/drivers/edac/al_l1_edac.c
> > @@ -0,0 +1,190 @@
>
> > +#include <asm/sysreg.h>
> > +#include <linux/bitfield.h>
> > +#include <linux/of.h>
> > +#include <linux/smp.h>
>
> You need <linux/platform_device.h> for platform_device_register_simple().

Will be added in next PS.

> [...]
>
> > +static void al_l1_edac_cpumerrsr_read_status(void *arg)
> > +{
>
> > +	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);
> > +	}
>
> What serialises these? You kick this off from on_each_cpu(), what stops two CPUs calling
> this at the same time? 'edac_dev->counters.ce_count += count;' will go wrong in this case.
>
> I think you need a spinlock around the edac_device_* calls that take edac_dev so that only
> one occurs at a time.

Agree with you, will add spinlock in next PS.

> > +}
> > +
> > +static void al_l1_edac_check(struct edac_device_ctl_info *edac_dev)
> > +{
> > +	on_each_cpu(al_l1_edac_cpumerrsr_read_status, edac_dev, 1);
> > +}
> > +
> > +static int al_l1_edac_probe(struct platform_device *pdev)
> > +{
> > +	struct edac_device_ctl_info *edac_dev;
> > +	struct device *dev = &pdev->dev;
> > +	int ret;
> > +
> > +	edac_dev = edac_device_alloc_ctl_info(0, DRV_NAME, 1, "L", 1, 1, NULL,
> > +					      0, edac_device_alloc_index());
> > +	if (!edac_dev)
> > +		return -ENOMEM;
> > +
> > +	edac_dev->edac_check = al_l1_edac_check;
> > +	edac_dev->dev = dev;
> > +	edac_dev->mod_name = DRV_NAME;
> > +	edac_dev->dev_name = dev_name(dev);
> > +	edac_dev->ctl_name = "L1_cache";
> > +	platform_set_drvdata(pdev, edac_dev);
> > +
> > +	ret = edac_device_add_device(edac_dev);
> > +	if (ret)
> > +		goto err;
> > +
> > +	return 0;
> > +err:
>
> (this goto has one user, meaning you can remove it by restructuring the code)

Will be fixed in next PS.

> > +	dev_err(dev, "Failed to add L1 edac device (%d)\n", ret);
> > +	edac_device_free_ctl_info(edac_dev);
> > +
> > +	return ret;
> > +}
> > +
>
> > +static const struct of_device_id al_l1_edac_of_match[] = {
> > +	{ .compatible = "al,alpine-v2" },
> > +	{ .compatible = "amazon,alpine-v3" },
> > +	{}
> > +};
>
> Unusually these are machine compatibles. It may be worth a comment that these are the
> platforms which are known to have Cortex-A57/A72 configured with this support, and access
> to the registers enabled by firmware.

Will be added.

> > +MODULE_DEVICE_TABLE(of, al_l1_edac_of_match);
>
> [..]
>
> > +static int __init al_l1_init(void)
> > +{
> > +	struct device_node *root = of_find_node_by_path("/");
> > +	int ret;
>
> root could be NULL here.

Will be fixed.

> > +	if (!of_match_node(al_l1_edac_of_match, root))
> > +		return 0;
> > +
> > +	ret = platform_driver_register(&al_l1_edac_driver);
> > +	if (ret) {
> > +		pr_err("Failed to register %s (%d)\n", DRV_NAME, ret);
> > +		return ret;
> > +	}
> > +
> > +	edac_l1_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0);
> > +	if (IS_ERR(edac_l1_device)) {
> > +		pr_err("Failed to register EDAC AL L1 platform device\n");
> > +		return PTR_ERR(edac_l1_device);
> > +	}
> > +
> > +	return 0;
> > +}
>
> With the edac_device_handle_ce() race fixed:
> Reviewed-by: James Morse <james.morse@xxxxxxx>

Thanks,
Hanna

> Thanks,
>
> James