Re: [PATCH v6 02/11] powerpc/powernv: Autoload IMC device driver module

[Madhavan Srinivasan]

On Tuesday 04 April 2017 06:28 AM, Daniel Axtens wrote:
> Hi all,
>
> I'm trying to get my head around these patches - at this point I'm just
> doing a first pass, so I may have more substantive structural comments
> later on. In the mean time - here are some minor C nits:
>
> > + * Copyright	(C) 2016 Madhavan Srinivasan, IBM Corporation.
> > + *		(C) 2016 Hemant K Shaw, IBM Corporation.
> Should these be bumped to 2017?

Facepalm. my bad. Will fix it.
> > +
> > +		do {
> > +			pages = PAGE_SIZE * i;
> > +			pcni->vbase[i++] = (u64)phys_to_virt(pcni->pbase +
> > +							     pages);
> > +		} while (i < (pcni->size / PAGE_SIZE));
> > +	}
> I had to scroll back up to the top of this function to make sure I
> understood what this loop does. Would it be better to write it as:
>
> for (i = 0; i < (pcni->size / PAGE_SIZE); i++) {
>      pages = PAGE_SIZE * i;
>      pcni->vbase[i] = (u64)....
> }
Idea is to map all of the nest counter area since event
offset could be anywhere within this region.
Will document that here.

> And, just checking - this is expected to work on both 4 and 64kB pages?
Yes. thats the intended. That said, i need to fix the
IMC_NEST_MAX_PAGES value for 4K page size.
Reason being, there was a recent change in the
size of memory allocated for nest counters in the
HOMER region for the microcode.

> > +
> > +	return 0;
> > +err:
> > +	return -ENODEV;
> You're not releasing any resources here - would it be better to just
> replace the gotos with this return? I haven't checked to see if you
> change the function later on to allocate memory - if so please ignore :)

We check in multiple places in the function and return on fail.
Thats why we made it as a generic return with goto.


> > +}
> > +
> > +static const struct of_device_id opal_imc_match[] = {
> > +	{ .compatible = IMC_DTB_COMPAT },
> > +	{},
> > +};
> > +
> > +static struct platform_driver opal_imc_driver = {
> > +	.driver = {
> > +		.name = "opal-imc-counters",
> > +		.of_match_table = opal_imc_match,
> > +	},
> > +	.probe = opal_imc_counters_probe,
> > +};
> > +
> > +MODULE_DEVICE_TABLE(of, opal_imc_match);
> > +module_platform_driver(opal_imc_driver);
> > +MODULE_DESCRIPTION("PowerNV OPAL IMC driver");
> > +MODULE_LICENSE("GPL");
> > diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> > index e0f856bfbfe8..85ea1296f030 100644
> > --- a/arch/powerpc/platforms/powernv/opal.c
> > +++ b/arch/powerpc/platforms/powernv/opal.c
> > @@ -14,6 +14,7 @@
> >   #include <linux/printk.h>
> >   #include <linux/types.h>
> >   #include <linux/of.h>
> > +#include <linux/of_address.h>
> >   #include <linux/of_fdt.h>
> >   #include <linux/of_platform.h>
> >   #include <linux/interrupt.h>
> > @@ -30,6 +31,7 @@
> >   #include <asm/opal.h>
> >   #include <asm/firmware.h>
> >   #include <asm/mce.h>
> > +#include <asm/imc-pmu.h>
> >   
> >   #include "powernv.h"
> >   
> > @@ -631,6 +633,15 @@ static void opal_pdev_init(const char *compatible)
> >   		of_platform_device_create(np, NULL, NULL);
> >   }
> >   
> > +static void opal_imc_init_dev(void)
> > +{
> > +	struct device_node *np;
> > +
> > +	np = of_find_compatible_node(NULL, NULL, IMC_DTB_COMPAT);
> > +	if (np)
> > +		of_platform_device_create(np, NULL, NULL);
> > +}
> Should this function be tagged __init?

Yes. Thats right. Will make the changes.

Thanks for review
Maddy

> > +
> >   static int kopald(void *unused)
> >   {
> >   	unsigned long timeout = msecs_to_jiffies(opal_heartbeat) + 1;
> > @@ -704,6 +715,9 @@ static int __init opal_init(void)
> >   	/* Setup a heatbeat thread if requested by OPAL */
> >   	opal_init_heartbeat();
> >   
> > +	/* Detect IMC pmu counters support and create PMUs */
> > +	opal_imc_init_dev();
> > +
> >   	/* Create leds platform devices */
> >   	leds = of_find_node_by_path("/ibm,opal/leds");
> >   	if (leds) {
> > --
> > 2.7.4