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Message-ID: <b90d3b99-a4d2-86f5-be9a-803b33d787b6@arm.com>
Date: Mon, 27 Mar 2023 15:27:39 +0100
From: Robin Murphy <robin.murphy@....com>
To: Will Deacon <will@...nel.org>,
Jing Zhang <renyu.zj@...ux.alibaba.com>,
ilkka@...amperecomputing.com
Cc: Mark Rutland <mark.rutland@....com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Shuai Xue <xueshuai@...ux.alibaba.com>,
Zhuo Song <zhuo.song@...ux.alibaba.com>
Subject: Re: [PATCH] perf/arm-cmn: Fix and refactor device mapping resource
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@...ux.alibaba.com>
>> ---
>> 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
>>
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