Re: [PATCH RFC v3 08/11] ACPI: PPTT: Add acpi_pptt_get_cache_size_from_id helper

From: Reinette Chatre <reinette.chatre@intel.com>
To: "Drew Fustini" <fustini@kernel.org>,
	"Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	"Radim Krčmář" <rkrcmar@ventanamicro.com>,
	"Samuel Holland" <samuel.holland@sifive.com>,
	"Adrien Ricciardi" <aricciardi@baylibre.com>,
	"Nicolas Pitre" <npitre@baylibre.com>,
	"Kornel Dulęba" <mindal@semihalf.com>,
	"Atish Patra" <atish.patra@linux.dev>,
	"Atish Kumar Patra" <atishp@rivosinc.com>,
	"Vasudevan Srinivasan" <vasu@rivosinc.com>,
	"Ved Shanbhogue" <ved@rivosinc.com>,
	"Conor Dooley" <conor.dooley@microchip.com>,
	"yunhui cui" <cuiyunhui@bytedance.com>,
	"Chen Pei" <cp0613@linux.alibaba.com>,
	"Liu Zhiwei" <zhiwei_liu@linux.alibaba.com>,
	"Weiwei Li" <liwei1518@gmail.com>,
	guo.wenjia23@zte.com.cn,
	"Gong Shuai" <gong.shuai@sanechips.com.cn>,
	"Gong Shuai" <gsh517@gmail.com>,
	liu.qingtao2@zte.com.cn, "Tony Luck" <tony.luck@intel.com>,
	"Babu Moger" <babu.moger@amd.com>,
	"Peter Newman" <peternewman@google.com>,
	"Fenghua Yu" <fenghua.yu@intel.com>,
	"James Morse" <james.morse@arm.com>,
	"Ben Horgan" <ben.horgan@arm.com>,
	"Dave Martin" <Dave.Martin@arm.com>,
	"Rob Herring" <robh@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	"Len Brown" <lenb@kernel.org>,
	"Robert Moore" <robert.moore@intel.com>,
	"Sunil V L" <sunilvl@ventanamicro.com>
Cc: <linux-kernel@vger.kernel.org>, <linux-riscv@lists.infradead.org>,
	<x86@kernel.org>, <linux-acpi@vger.kernel.org>,
	<acpica-devel@lists.linux.dev>, <devicetree@vger.kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>
Subject: Re: [PATCH RFC v3 08/11] ACPI: PPTT: Add acpi_pptt_get_cache_size_from_id helper
Date: Thu, 30 Apr 2026 16:20:23 -0700	[thread overview]
Message-ID: <4fa25edf-65eb-4ff6-bb52-a7087490e81d@intel.com> (raw)
In-Reply-To: <20260414-ssqosid-cbqri-rqsc-v7-0-v3-8-b3b2e7e9847a@kernel.org>

Hi Drew,

On 4/14/26 6:54 PM, Drew Fustini wrote:
> Add helper to look up a cache's size from its cache ID in the PPTT
> table. This is needed by the RISC-V RQSC parser to determine the cache
> size for CBQRI capacity controllers.
> 
> The implementation follows the pattern established by
> find_acpi_cache_level_from_id() and acpi_pptt_get_cpumask_from_cache_id():
> uses acpi_get_pptt(), upgrade_pptt_cache(), checks all three cache types,
> and uses the do/while empty-detection loop.

I see how this helper is used to initialize cbqri_controller::cache::cache_size
but I am not able to determine where this value is used.
resctrl does need the cache size but it currently relies on struct cacheinfo returned
by the get_cpu_cacheinfo_level() helper to obtain it.

Reinette