Re: [U-Boot] [PATCH v5 6/8] ARMv7: PSCI: ls102xa: check ALREADY_ON or ON_PENDING for CPU_ON

On Tue, Jun 28, 2016 at 12:30 PM, Chen-Yu Tsai wens@csie.org wrote:

On Tue, Jun 14, 2016 at 3:01 PM, macro.wave.z@gmail.com wrote:

...

From: Hongbo Zhang hongbo.zhang@nxp.com

For the robustness of codes, while powering on a CPU, it is better to check if the target CPU is already on or in the process of power on, if yes the power on routine shouldn't be executed further and should return with the corresponding status immediately.

Signed-off-by: Hongbo Zhang hongbo.zhang@nxp.com

arch/arm/cpu/armv7/ls102xa/psci.S | 29 +++++++++++++++++++++++++++++ arch/arm/include/asm/psci.h | 5 +++++ 2 files changed, 34 insertions(+)

diff --git a/arch/arm/cpu/armv7/ls102xa/psci.S b/arch/arm/cpu/armv7/ls102xa/psci.S index a4482e4..0188ade 100644 --- a/arch/arm/cpu/armv7/ls102xa/psci.S +++ b/arch/arm/cpu/armv7/ls102xa/psci.S @@ -66,6 +66,22 @@ psci_cpu_on: beq out_psci_cpu_on mov r1, r0

•   bl      psci_get_cpu_stack_top
  

•   sub     r0, r0, #PSCI_CPU_STATUS_OFFSET
  

•   ldr     r5, [r0]
  

•   cmp     r5, #PSCI_CPU_STATUS_ON
  

•   moveq   r0, #ARM_PSCI_RET_ALREADY_ON
  

•   beq     out_psci_cpu_on
  

•   cmp     r5, #PSCI_CPU_STATUS_ON_PENDING
  

•   moveq   r0, #ARM_PSCI_RET_ON_PENDING
  

•   beq     out_psci_cpu_on
  

•   mov     r5, #PSCI_CPU_STATUS_ON_PENDING
  

•   str     r5, [r0]
  

•   dsb
  

•   bl      psci_cpu_on_common
  
    @ Get DCFG base address
  

@@ -123,6 +139,12 @@ holdoff_release: rev r6, r6 str r6, [r4, #DCFG_CCSR_SCRATCHRW1]

•   mov     r0, r1
  

•   bl      psci_get_cpu_stack_top
  

•   sub     r0, r0, #PSCI_CPU_STATUS_OFFSET
  

•   mov     r5, #PSCI_CPU_STATUS_ON
  

•   str     r5, [r0]
  

•   isb
    dsb
  
  

@@ -137,6 +159,13 @@ out_psci_cpu_on: psci_cpu_off: bl psci_cpu_off_common

•   bl      psci_get_cpu_id
  

•   bl      psci_get_cpu_stack_top
  

•   sub     r0, r0, #PSCI_CPU_STATUS_OFFSET
  

•   mov     r5, #PSCI_CPU_STATUS_OFF
  

•   str     r5, [r0]
  

•   dsb
  

psci_cpu_off_common flushes and disables caches, and turns off SMP. So the code you're adding might not work as expected? ARM folks might know more.

Moving this code ahead of psci_cpu_off_common seems better? I just though such a code should be placed as later as it can.

The rest looks good, though I expect them to be pulled out into common helpers and rewritten in C. :)

Regards ChenYu

...

1: wfi b 1b

diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h index bedcd30..89a1ba5 100644 --- a/arch/arm/include/asm/psci.h +++ b/arch/arm/include/asm/psci.h @@ -67,6 +67,11 @@ #define PSCI_PERCPU_STACK_SIZE 0x400 #define PSCI_TARGET_PC_OFFSET (PSCI_PERCPU_STACK_SIZE - 4) #define PSCI_CONTEXT_ID_OFFSET (PSCI_PERCPU_STACK_SIZE - 8) +#define PSCI_CPU_STATUS_OFFSET (PSCI_PERCPU_STACK_SIZE - 12)

+#define PSCI_CPU_STATUS_OFF 0 +#define PSCI_CPU_STATUS_ON 1 +#define PSCI_CPU_STATUS_ON_PENDING 2

#ifndef __ASSEMBLY__ int psci_update_dt(void *fdt); -- 2.1.4