Re: [PATCH] perf/arm-cmn: Fix and refactor device mapping resource

[Robin Murphy]

On 2023-03-27 15:05, Will Deacon wrote:
> [+Robin and Ilkka, as they contribute most to this driver]
>
> On Thu, Feb 16, 2023 at 04:17:50PM +0800, Jing Zhang wrote:
> > The devm_platform_ioremap_resource() won't let the platform device
> > claim resource when the ACPI companion device has already claimed it.
> > If CMN-ANY except CMN600 is ACPI companion device, it will return
> > -EBUSY in devm_platform_ioremap_resource(), and the driver cannot be
> > successfully installed.
> >
> > So let ACPI companion device call arm_cmn_acpi_probe and not claim
> > resource again. In addition, the arm_cmn_acpi_probe() and
> > arm_cmn_of_probe() functions are refactored to make them compatible
> > with both CMN600 and CMN-ANY.

No, the whole point of CMN-600 probing being a special case is that the 
ACPI and DT bindings for CMN-600 are special cases. In ACPI, only 
ARMHC600 has the two nested memory resources; all the other models 
should only have one memory resource because one is all that is 
meaningful. See table 16 the document[1] in where the description of 
ROOTNODEBASE says "This field is specific to the CMN-600 device object."

Similarly in DT, "arm,root-node" is only required for "arm,cmn-600" - it 
didn't seem worth overcomplicating the schema to actively disallow it 
for other models, but that is supposed to be implied by its description 
as "not relevant for newer CMN/CI products".

If you're hitting this because you've written your ACPI DSDT 
incorrectly, it's a sign that you should fix your DSDT.

Thanks,
Robin.

[1] https://developer.arm.com/documentation/den0093/latest/

> > Fixes: 61ec1d875812 ("perf/arm-cmn: Demarcate CMN-600 specifics")
> > Signed-off-by: Jing Zhang <renyu.zj@xxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/perf/arm-cmn.c | 57 ++++++++++++++++++++++++++++++++------------------
> >   1 file changed, 37 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> > index 1deb61b..beb3b37 100644
> > --- a/drivers/perf/arm-cmn.c
> > +++ b/drivers/perf/arm-cmn.c
> > @@ -2206,7 +2206,7 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
> >   	return 0;
> >   }
> >   
> > -static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *cmn)
> > +static int arm_cmn_acpi_probe(struct platform_device *pdev, struct arm_cmn *cmn)
> >   {
> >   	struct resource *cfg, *root;
> >   
> > @@ -2214,12 +2214,21 @@ static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *c
> >   	if (!cfg)
> >   		return -EINVAL;
> >   
> > -	root = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > -	if (!root)
> > -		return -EINVAL;
> > +	/* If ACPI defines more than one resource, such as cmn-600, then there may be
> > +	 * a deviation between ROOTNODEBASE and PERIPHBASE, and ROOTNODEBASE can
> > +	 * be obtained from the second resource. Otherwise, it can be considered that
> > +	 * ROOT NODE BASE is PERIPHBASE. This is compatible with cmn-600 and cmn-any.
> > +	 */
> > +	if (pdev->num_resources > 1) {
> > +		root = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > +		if (!root)
> > +			return -EINVAL;
> >   
> > -	if (!resource_contains(cfg, root))
> > -		swap(cfg, root);
> > +		if (!resource_contains(cfg, root))
> > +			swap(cfg, root);
> > +	} else {
> > +		root = cfg;
> > +	}
> >   	/*
> >   	 * Note that devm_ioremap_resource() is dumb and won't let the platform
> >   	 * device claim cfg when the ACPI companion device has already claimed
> > @@ -2227,17 +2236,30 @@ static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *c
> >   	 * appropriate name, we don't really need to do it again here anyway.
> >   	 */
> >   	cmn->base = devm_ioremap(cmn->dev, cfg->start, resource_size(cfg));
> > -	if (!cmn->base)
> > -		return -ENOMEM;
> > +	if (IS_ERR(cmn->base))
> > +		return PTR_ERR(cmn->base);
> >   
> >   	return root->start - cfg->start;
> >   }
> >   
> > -static int arm_cmn600_of_probe(struct device_node *np)
> > +static int arm_cmn_of_probe(struct platform_device *pdev, struct arm_cmn *cmn)
> >   {
> >   	u32 rootnode;
> > +	int ret;
> > +
> > +	cmn->base = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(cmn->base))
> > +		return PTR_ERR(cmn->base);
> >   
> > -	return of_property_read_u32(np, "arm,root-node", &rootnode) ?: rootnode;
> > +	/* If of_property_read_u32() return EINVAL, it means that device tree has
> > +	 * not define root-node, and root-node will return 0, which is compatible
> > +	 * with cmn-600 and cmn-any.
> > +	 */
> > +	ret = of_property_read_u32(pdev->dev.of_node, "arm,root-node", &rootnode);
> > +	if (ret == -EINVAL)
> > +		return 0;
> > +
> > +	return rootnode;
> >   }
> >   
> >   static int arm_cmn_probe(struct platform_device *pdev)
> > @@ -2255,16 +2277,11 @@ static int arm_cmn_probe(struct platform_device *pdev)
> >   	cmn->model = (unsigned long)device_get_match_data(cmn->dev);
> >   	platform_set_drvdata(pdev, cmn);
> >   
> > -	if (cmn->model == CMN600 && has_acpi_companion(cmn->dev)) {
> > -		rootnode = arm_cmn600_acpi_probe(pdev, cmn);
> > -	} else {
> > -		rootnode = 0;
> > -		cmn->base = devm_platform_ioremap_resource(pdev, 0);
> > -		if (IS_ERR(cmn->base))
> > -			return PTR_ERR(cmn->base);
> > -		if (cmn->model == CMN600)
> > -			rootnode = arm_cmn600_of_probe(pdev->dev.of_node);
> > -	}
> > +	if (has_acpi_companion(cmn->dev))
> > +		rootnode = arm_cmn_acpi_probe(pdev, cmn);
> > +	else
> > +		rootnode = arm_cmn_of_probe(pdev, cmn);
> > +
> >   	if (rootnode < 0)
> >   		return rootnode;
> >   
> > --
> > 1.8.3.1