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Sat, 10 Sep 2022 15:35:59 +0100 Date: Sat, 10 Sep 2022 15:35:59 +0100 Message-ID: <87y1urpa9c.wl-maz@kernel.org> From: Marc Zyngier To: Frank Li Cc: "tglx@linutronix.de" , "robh+dt@kernel.org" , "krzysztof.kozlowski+dt@linaro.org" , "shawnguo@kernel.org" , "s.hauer@pengutronix.de" , "kw@linux.com" , "bhelgaas@google.com" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-pci@vger.kernel.org" , Peng Fan , Aisheng Dong , "jdmason@kudzu.us" , "kernel@pengutronix.de" , "festevam@gmail.com" , dl-linux-imx , "kishon@ti.com" , "lorenzo.pieralisi@arm.com" , "ntb@lists.linux.dev" , "lznuaa@gmail.com" , "imx@lists.linux.dev" , "manivannan.sadhasivam@linaro.org" Subject: Re: [EXT] Re: [PATCH v9 2/4] irqchip: Add IMX MU MSI controller driver In-Reply-To: References: <20220907034856.3101570-1-Frank.Li@nxp.com> <20220907034856.3101570-3-Frank.Li@nxp.com> <87fsh2qpq4.wl-maz@kernel.org> <877d2dvs0d.wl-maz@kernel.org> <87edwkrbs4.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: frank.li@nxp.com, tglx@linutronix.de, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, shawnguo@kernel.org, s.hauer@pengutronix.de, kw@linux.com, bhelgaas@google.com, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, peng.fan@nxp.com, aisheng.dong@nxp.com, jdmason@kudzu.us, kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, kishon@ti.com, lorenzo.pieralisi@arm.com, ntb@lists.linux.dev, lznuaa@gmail.com, imx@lists.linux.dev, manivannan.sadhasivam@linaro.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220910_073603_593225_0BB78B2B X-CRM114-Status: GOOD ( 23.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 09 Sep 2022 15:59:01 +0100, Frank Li wrote: > > > > > > > [Frank Li] According to my understand, raw_spinlock skip some lockdep > > > /debug feature to get better performance, which should be used when > > > Frequently call, such as irq handle\polling thread. > > > > I'm afraid you are terribly misguided. They both have the same debug > > features because they are both using the same core implementation, and > > the only difference is whether this is preemptible for RT purposes or > > not. > > > > > Spinlock have DEBUG feature to check wrong use lock. Allocate MSI > > generally > > > only is call once when driver probe. > > > > Again, you should really read the code and the documentation and stop > > making things up. > > [Frank Li] Thanks. You give me the correct direction. Some stackoverflow's > Doc was misleaded. I double checked spin_lock implementation. PREEMPT_RT > Kernel map spin_lock to rt_mutex. > > I am curious why exist spin_lock_irqsave and raw_spin_lock_irqsave before > PREEMTP_RT merge into kernel tree. Because the RT merge has been going on for 10 years or so, long before CONFIG_RT was merged. Also, a mutex has a spin lock at its core, and it makes sense to have a single primitive for all these lock types. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel