From mboxrd@z Thu Jan 1 00:00:00 1970 From: geoff@infradead.org (Geoff Levand) Date: Thu, 17 Apr 2014 11:17:03 -0700 Subject: [PATCH] arm64: Fix PSCI part of booting.txt Message-ID: <1397758623.30572.53.camel@smoke> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Correct the PSCI booting text to match the requirements of the PSCI spec. Signed-off-by: Geoff Levand --- Hi Will, Based on the PSCI doc (DEN 0022B.b), to use CPU_ON the cpu can only be powered down with CPU_OFF, and it seems from the doc that the code that calls CPU_OFF could be anywhere in memory, since once the CPU_OFF call is made the cpu is powered off and never executes any more instructions from memory. CPU_ON is given an entry_point_address parameter, which would be specific to the code calling CPU_ON. Did I misunderstand something, or should we change this text as below? -Geoff Documentation/arm64/booting.txt | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt index beb754e..8f9074f 100644 --- a/Documentation/arm64/booting.txt +++ b/Documentation/arm64/booting.txt @@ -167,13 +167,12 @@ following manner: value, so CPUs must convert the read value to their native endianness before jumping to it. -- CPUs with a "psci" enable method should remain outside of - the kernel (i.e. outside of the regions of memory described to the - kernel in the memory node, or in a reserved area of memory described - to the kernel by a /memreserve/ region in the device tree). The - kernel will issue CPU_ON calls as described in ARM document number ARM - DEN 0022A ("Power State Coordination Interface System Software on ARM - processors") to bring CPUs into the kernel. +- CPUs with a "psci" enable method should use the PSCI CPU control + functions described in ARM document number ARM DEN 0022A or newer + ("Power State Coordination Interface System Software on ARM + processors"). The boot loader must power off these CPU's using the + PSCI CPU_OFF function. The kernel will issue CPU_ON calls to bring + CPUs into the kernel. The device tree should contain a 'psci' node, as described in Documentation/devicetree/bindings/arm/psci.txt. -- 1.9.1