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Tue, 27 Oct 2015 05:22:39 -0700 (PDT) Received: by 10.182.214.104 with HTTP; Tue, 27 Oct 2015 05:22:39 -0700 (PDT) In-Reply-To: <562F6799.1060301@arm.com> References: <1444904415-19597-1-git-send-email-linus.walleij@linaro.org> <561FC681.2040809@arm.com> <5624C31D.3070906@arm.com> <20151019102932.GB10678@leverpostej> <20151019113904.GE10678@leverpostej> <20151020112026.GF10728@bivouac.eciton.net> <562F6799.1060301@arm.com> Date: Tue, 27 Oct 2015 13:22:39 +0100 Message-ID: Subject: Re: [PATCH] ARM64: juno: add NOR flash to device tree From: Linus Walleij To: Sudeep Holla X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151027_052301_327115_8DD12C83 X-CRM114-Status: GOOD ( 23.45 ) X-Spam-Score: -2.6 (--) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [2607:f8b0:4003:c01:0:0:0:22a listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Lorenzo Pieralisi , Catalin Marinas , Liviu Dudau , Leif Lindholm , Ryan Harkin , "arm@kernel.org" , "linux-arm-kernel@lists.infradead.org" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patch=linaro.org@lists.infradead.org On Tue, Oct 27, 2015 at 1:01 PM, Sudeep Holla wrote: > On 27/10/15 11:55, Linus Walleij wrote: >> On Wed, Oct 21, 2015 at 12:07 PM, Ryan Harkin >> wrote: >> >>> FYI, in the latest Juno motherboard firmware [1], I have a file called >>> "blank.img" in the NOR flash at address 0x0BFC0000 that represents the >>> UEFI >>> (and now u-boot) config area at the end of the NOR flash. >>> >>> I mostly put this there so that you can "touch blank.img" to erase the >>> config, but also to show that the region is reserved to anyone who might >>> think about putting something there. >> >> >> Then it is safe to enable NOR flash and AFS in the kernel. > > *No*, not on Juno. If we need to enable them for other platforms, then > we should either disable NOR flash in DT(or even remove it completely > whichever is appropriate). > > Since idle is enable in defconfig and if DT has idle states, then it > can't boot for the reason I previously mentioned. Yeah right I remember that now. Let's say it is safe to enable for the tamper-security reason. There may be other reasons not to... If this is about different idle functionalities blocking flash access, what we should do is to in Kconfig make it impossible to compile in both deep idle states and flash support at the same time, as that is how the system really behaves. I.e do you mean something like this, or am I getting it wrong? index 21340e0be73e..07d91776bcfe 100644 Hiding hardware from the devicetree seems over the top to me, it is better to keep the device trees describing the actual hardware and the operating system to figure out how things need to be set up to interoperate, at config-time or run-time. Yours, Linus Walleij _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --- a/drivers/cpuidle/Kconfig.arm +++ b/drivers/cpuidle/Kconfig.arm @@ -4,6 +4,7 @@ config ARM_CPUIDLE bool "Generic ARM/ARM64 CPU idle Driver" select DT_IDLE_STATES + depends on !(ARCH_VEXPRESS && MTD) help Select this to enable generic cpuidle driver for ARM. It provides a generic idle driver whose idle states are configured