linux-kernel - Re: [PATCH V8 5/8] irqchip/gicv3-its: Refactor ITS DT init code to prepare for ACPI

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Message-ID: <20160817155832.GA25421@localhost>
Date:	Wed, 17 Aug 2016 10:58:32 -0500
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Hanjun Guo <guohanjun@...wei.com>
Cc:	Tomasz Nowicki <tn@...ihalf.com>, marc.zyngier@....com,
	tglx@...utronix.de, jason@...edaemon.net, rjw@...ysocki.net,
	rafael@...nel.org, Lorenzo.Pieralisi@....com, will.deacon@....com,
	catalin.marinas@....com, hanjun.guo@...aro.org,
	shijie.huang@....com, robert.richter@...iumnetworks.com,
	mw@...ihalf.com, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linaro-acpi@...ts.linaro.org,
	andrea.gallo@...aro.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, al.stone@...aro.org,
	graeme.gregory@...aro.org, ddaney.cavm@...il.com,
	okaya@...eaurora.org
Subject: Re: [PATCH V8 5/8] irqchip/gicv3-its: Refactor ITS DT init code to
 prepare for ACPI

On Wed, Aug 17, 2016 at 04:33:02PM +0800, Hanjun Guo wrote:
> On 2016/8/11 18:06, Tomasz Nowicki wrote:
> > In order to add ACPI support we need to isolate ACPI&DT common code and
> > move DT logic to corresponding functions. To achieve this we are using
> > firmware agnostic handle which can be unpacked to either DT or ACPI node.
> >
> > No functional changes other than a very minor one:
> > 1. Terminate its_init call with -ENODEV for non-DT case which allows
> > to remove hack from its-gic-v3.c.
> > 2. Fix ITS base register address type (from 'unsigned long' to 'phys_addr_t'),
> > as a bonus we get nice string formatting.
> > 3. Since there is only one of ITS parent domain convert it to static global
> > variable and drop the parameter from its_probe_one. Users can refer to it
> > in more convenient way then.
> [...]
> > -static int __init its_probe(struct device_node *node,
> > -			    struct irq_domain *parent)
> > +static int __init its_probe_one(struct resource *res,
> > +				struct fwnode_handle *handle, int numa_node)
> >  {
> > -	struct resource res;
> >  	struct its_node *its;
> >  	void __iomem *its_base;
> >  	u32 val;
> >  	u64 baser, tmp;
> >  	int err;
> >  
> > -	err = of_address_to_resource(node, 0, &res);
> > -	if (err) {
> > -		pr_warn("%s: no regs?\n", node->full_name);
> > -		return -ENXIO;
> > -	}
> > -
> > -	its_base = ioremap(res.start, resource_size(&res));
> > +	its_base = ioremap(res->start, resource_size(res));
> >  	if (!its_base) {
> > -		pr_warn("%s: unable to map registers\n", node->full_name);
> > +		pr_warn("ITS@%pa: Unable to map ITS registers\n", &res->start);
> >  		return -ENOMEM;
> >  	}
> >  
> >  	val = readl_relaxed(its_base + GITS_PIDR2) & GIC_PIDR2_ARCH_MASK;
> >  	if (val != 0x30 && val != 0x40) {
> > -		pr_warn("%s: no ITS detected, giving up\n", node->full_name);
> > +		pr_warn("ITS@%pa: No ITS detected, giving up\n", &res->start);
> >  		err = -ENODEV;
> >  		goto out_unmap;
> >  	}
> >  
> >  	err = its_force_quiescent(its_base);
> >  	if (err) {
> > -		pr_warn("%s: failed to quiesce, giving up\n",
> > -			node->full_name);
> > +		pr_warn("ITS@%pa: Failed to quiesce, giving up\n", &res->start);
> >  		goto out_unmap;
> >  	}
> >  
> > -	pr_info("ITS: %s\n", node->full_name);
> > +	pr_info("ITS@%pa\n", &res->start);
>                 ^^
> 
> When I was testing this patch set I found message printed as below:
> 
> [    0.000000] ITS@...0000000c6000000

I think it'd be nicer to print the resource with %pR so we see the
type and size in a way that matches other physical address usage.

I don't know whether there is or should be a struct device associated
with the ITS.  The its_probe_one() function looks similar to regular
driver probe functions, so maybe there should be.

If there were a struct device associated with the ITS, it'd be nicer
to use dev_info() as well, of course.

> [    0.000000] ITS@...0000000c6000000: allocated 524288 Devices @27dc400000 (flat, esz 8, psz 16K, shr 1)
> [    0.000000] ITS@...0000000c6000000: allocated 2048 Virtual CPUs @27dc820000 (flat, esz 8, psz 4K, shr 1)
> [    0.000000] ITS@...0000000c6000000: allocated 512 Interrupt Collections @27dc80f000 (flat, esz 8, psz 4K, shr 1)
> 
> Seems this print is redundant, can we remove it?
> 
> Thanks
> Hanjun
>