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([39.170.101.209]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ae8454327esm8980297a91.4.2026.10.31.19.55.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 31 Oct 2026 19:55:54 -0700 (PDT) From: Ping Li To: ben.horgan@arm.com, james.morse@arm.com Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, reinette.chatre@intel.com, fenghuay@nvidia.com Subject: Re: [PATCH] arm_mpam: Warn when firmware leaves PARTIDs disabled Date: Sun, 1 Nov 2026 10:55:50 +0800 Message-Id: <20261101025550.1633447-1-leeonion.muyu@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <8950f9bc-8ca9-476c-a7d6-2b434908b80c@arm.com> References: <8950f9bc-8ca9-476c-a7d6-2b434908b80c@arm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Ben, Thanks for sharing the direction. I asked our hardware team why they implemented HAS_ENDIS: the motivation is power. Enabling PARTIDs that are never used does not affect performance, but costs leakage in the registers and combinational logic behind them - with e.g. 32 PARTIDs implemented and only a handful ever used, the unused portion is pure waste. Their expectation was that software would enable only the PARTIDs it needs at initialization time. For a general-purpose driver that cannot predict how many PARTIDs userspace will actually use, that is not something we can do. So what I plan to do is either enable all the PARTIDs from the driver, or ask the hardware team to drop the HAS_ENDIS feature. I am happy to drop this warning patch in favour of your driver-side enabling patch. Thanks, Ping