linux-kernel - Re: [PATCH 10/33] arm_mpam: Add probe/remove for mpam msc driver and kbuild boiler plate

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Message-ID: <9f00c748-c3cd-4f31-aefd-b27a4af343be@arm.com>
Date: Wed, 10 Sep 2025 20:31:18 +0100
From: James Morse <james.morse@....com>
To: "Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-arm-kernel@...ts.infradead.org"
 <linux-arm-kernel@...ts.infradead.org>,
 "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
 "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Cc: "shameerali.kolothum.thodi@...wei.com"
 <shameerali.kolothum.thodi@...wei.com>,
 D Scott Phillips OS <scott@...amperecomputing.com>,
 "carl@...amperecomputing.com" <carl@...amperecomputing.com>,
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 Lorenzo Pieralisi <lpieralisi@...nel.org>, Hanjun Guo
 <guohanjun@...wei.com>, Sudeep Holla <sudeep.holla@....com>,
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 <conor+dt@...nel.org>, Catalin Marinas <catalin.marinas@....com>,
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 Danilo Krummrich <dakr@...nel.org>
Subject: Re: [PATCH 10/33] arm_mpam: Add probe/remove for mpam msc driver and
 kbuild boiler plate

Hi Shaopeng,

On 09/09/2025 08:03, Shaopeng Tan (Fujitsu) wrote:
>> Probing MPAM is convoluted. MSCs that are integrated with a CPU may only be
>> accessible from those CPUs, and they may not be online.
>> Touching the hardware early is pointless as MPAM can't be used until the
>> system-wide common values for num_partid and num_pmg have been
>> discovered.
>>
>> Start with driver probe/remove and mapping the MSC.

>> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
>> new file mode 100644 index 000000000000..a0d9a699a6e7
>> --- /dev/null
>> +++ b/drivers/resctrl/mpam_devices.c
>> @@ -0,0 +1,336 @@

>> +static int mpam_dt_parse_resources(struct mpam_msc *msc, void *ignored)
>> +{
>> +	int err, num_ris = 0;
>> +	const u32 *ris_idx_p;
>> +	struct device_node *iter, *np;
>> +
>> +	np = msc->pdev->dev.of_node;
>> +	for_each_child_of_node(np, iter) {
>> +		ris_idx_p = of_get_property(iter, "reg", NULL);
>> +		if (ris_idx_p) {
>> +			num_ris++;
>> +			err = mpam_dt_parse_resource(msc, iter, *ris_idx_p);
>> +			if (err) {
>> +				of_node_put(iter);
>> +				return err;
>> +			}
>> +		}
>> +	}
>> +
>> +	if (!num_ris)
>> +		mpam_dt_parse_resource(msc, np, 0);

> err = mpam_dt_parse_resource(msc, np, 0);

Oops! Thanks for catching that,


James