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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cd3d9e07329sm6432925a12.5.2026.10.14.00.09.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Oct 2026 00:09:16 -0700 (PDT) Message-ID: <86fee017-c9cb-4583-beab-4f29919fb518@oss.qualcomm.com> Date: Wed, 14 Oct 2026 15:09:07 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH DNM v3 8/8] arm64: dts: qcom: kaanapali: Add MPAM MSC nodes for the L2 caches To: Ben Horgan , Rob Herring Cc: James Morse , Shanker Donthineni , Krzysztof Kozlowski , Conor Dooley , Catalin Marinas , Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Reinette Chatre , Fenghua Yu , Jonathan Cameron , Bjorn Andersson , Konrad Dybcio , Gavin Shan , Andre Przywara , Drew Fustini , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , Shaopeng Tan , trilok.soni@oss.qualcomm.com, aiqun.yu@oss.qualcomm.com, ganapatrao.kulkarni@oss.qualcomm.com, Srivathsa L Rao , Huang Yiwei , linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, devicetree@vger.kernel.org References: <20261008-mpam-resctrl-dt-knp-support-v3-0-35196c2b43bf@oss.qualcomm.com> <20261008-mpam-resctrl-dt-knp-support-v3-8-35196c2b43bf@oss.qualcomm.com> <20261008210004.GA1318789-robh@kernel.org> <1d764a3d-7935-4e26-b1c2-92537e1d3811@oss.qualcomm.com> <893507ca-b956-474c-9124-92fbfc25e9ab@arm.com> <6e06228b-827a-4321-99c1-3e0e961abd61@arm.com> Content-Language: en-US From: Yin Li In-Reply-To: <6e06228b-827a-4321-99c1-3e0e961abd61@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDE0MDAyOCBTYWx0ZWRfX4BplbxnhGm6K AOHQOh+xxACFmgfpi7cuR5zfmY6wpXoHZ3Vk/M7GQWRKa4Pya4bRg0GLkXOxvOiyCwh59/feb4a +br6g6IPrinzoUlydYjBOZ8Ym/hHV8L3yZgDlTBPs2IkFDmpjw0HOYqUw17h+1c8G33dWPmOE/D NBQuK3eG6GgbvGwRelufVc8KWE0J2oXAE7aXWrqUo8Q46wp9Sptnlo/q1FwF2mD+iTIfZMp/vjA L3gv0+GpRVgJuE/rqkkGLXhg/P/M09r7HOOnyDCCNYigTSCdHXKyqMlnB6R8XN/8DuPIrYNN+fT z0z0v9WyPO9jNJyhn1FRQGZxEt7iqhrEy4yytm/oHk/hiSYz16OutsN+RKkF/RS3Siy85jH3qo2 k4MC7d24FfDzaQjR6gsd4zVd7cqvRLOyh3dXitgUZ9p+aABjxrV+C0aAbe1rKWvxLfcyBt5DkYv 6gGAF2HMv14q4HI5jyA== X-Authority-Analysis: v=2.4 cv=LPPz05W9 c=1 sm=1 tr=0 ts=6acf2a9e cx=c_pps a=vVfyC5vLCtgYJKYeQD43oA==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yOCtJkima9RkubShWh1s:22 a=EUspDBNiAAAA:8 a=lWq2qqVSSi_Om9X4mrcA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=rl5im9kqc5Lf4LNbBjHf:22 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDE0MDAyOCBTYWx0ZWRfX16Evba8CJNi5 KkomSz+VdMtMmIppKUUeAAFhBmSt6WjISRz/fr7bVIf2gPt4t2wxyPZLI2rtjwODY0iU59Brq3U MpI3quEIRri3kTIW9hyKfO10rUGlP2M= X-Proofpoint-ORIG-GUID: lGGryA6c181g-wm08yzLWTdFYWjmxobs X-Proofpoint-GUID: lGGryA6c181g-wm08yzLWTdFYWjmxobs X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-13_01,2026-10-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 priorityscore=1501 clxscore=1015 adultscore=0 malwarescore=0 phishscore=0 lowpriorityscore=0 spamscore=0 suspectscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610140028 On 10/13/2026 6:37 PM, Ben Horgan wrote: > Hi Yin, > > On 13/10/2026 11:13, Yin Li wrote: >> >> >> On 10/12/2026 7:27 PM, Ben Horgan wrote: >>> Hi Yin, >>> >>> On 12/10/2026 11:48, Yin Li wrote: >>>> >>>> >>>> On 10/9/2026 5:00 AM, Rob Herring wrote: >>>>> On Thu, Oct 08, 2026 at 02:41:17PM +0800, Yin Li wrote: >>>>>> Add an MPAM MSC device node for each L2 cache. Each MSC is nested >>>>>> directly under its L2 cache node so that the cache node is the MSC's >>>>>> parent device and its CPU affinity is derived from that cache. >>>>>> >>>>>> The L2 cache nodes are placed directly under the root node. The root is >>>>>> the root of the physical address space, so each cache node only needs an >>>>>> identity 'ranges' property for its nested MSC's 'reg' to be resolved to >>>>>> a physical address. The two caches use distinct node names (l2-cache-0 >>>>>> and l2-cache-1) since a cache node has no MMIO unit-address of its own. >>>>>> >>>>>> The nodes are disabled by default. Production firmware does not expose >>>>>> MSC register access to the OS, so these nodes can only be enabled on a >>>>>> local test setup where firmware permits direct MMIO access to the MSCs. >>>>>> This DTS is therefore only an example for other platform DT authors and >>>>>> is not intended to be merged. >>>>>> >>>>>> Co-developed-by: Huang Yiwei >>>>>> Signed-off-by: Huang Yiwei >>>>>> Signed-off-by: Yin Li >>>>>> --- >>>>>>    arch/arm64/boot/dts/qcom/kaanapali.dtsi | 50 +++++++++++++++++++++++++-------- >>>>>>    1 file changed, 38 insertions(+), 12 deletions(-) >>>>>> >>>>>> diff --git a/arch/arm64/boot/dts/qcom/kaanapali.dtsi b/arch/arm64/boot/dts/qcom/kaanapali.dtsi >>>>>> index 131fd2a16c54..b1dcb1e9c570 100644 >>>>>> --- a/arch/arm64/boot/dts/qcom/kaanapali.dtsi >>>>>> +++ b/arch/arm64/boot/dts/qcom/kaanapali.dtsi >>> >>> [...] >>> >>>> >>>>>> + >>>>>> +        msc@19870000 { >>>>>> +            compatible = "arm,mpam-msc"; >>>>>> +            reg = <0x0 0x19870000 0x0 0x10000>; >>>>> >>>>> The MPAM register length is 0x321C. >>>>> >>>> >>>> You are right, the MPAM register space is 0x321c per the specification. >>>> Will update accordingly. >>> >>> That is the full extent but truncation is allowed by the architecture. >>> >>> Section B.9 9.2.3 Permitted truncation of an MPAM feature page IQGXFF it mentions >>> some conditions but these haven't been updated for the introduction of FEAT_MPAM_MSC_DOMAINS. >>> >>> Does your implementation have domains? >>> >> >> Hi Ben, >> >> Our implementation does not have domains. So 0x321c reflects the full feature page for MSC. > > Truncation is allowed when domains aren't implemented. I was just trying to say that that part of > the spec (9.2.3) is out of date and needs to updated as it doesn't take into account the possibility > of domains. > > It's only domain specific registers from 0x3000 unless you have some implementation defined > registers (9.1.5). Is that whole region just reserved for MPAM anyway? > Hi Ben, Konrad, The original 0x10000 reflects the per-MSC register block size as allocated in the KNP hardware — as Konrad noted, Qualcomm DTs tend to use "how much register space is allocated for this block" rather than "what the last used register ends" to avoid holes. We'd like to update it to 0x321c to give other platform authors a more useful reference, without exposing KNP-internal details such as address holes between blocks. In our case, we don't implement MPAMCFG_MBW_PBM, and — as you noted — the registers from 0x3000 onward are domain-specific; since we have no domains, those aren't used either. So the actual footprint we need is smaller than 0x321c, but showing the full 0x321c gives other authors a complete picture of the allocated register space. That said, this patch is marked DNM and is intended as a local verification example only, not for merging. Thanks, Yin > Thanks, > > Ben > >> >> Thanks, >> Yin >> >> >>> Thanks, >>> >>> Ben >>> >>> >>>> >>>> Thanks, >>>> Yin >>>> >>>>> Rob >>>> >>> >> > -- Thx and BRs, Yin