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arch/arm/include/armv7-m/nvicpri.h: In the 'normal' case, the priority of the SVCALL interrupt was the same as the priority of the high priority interrupt. This means that SVCALL interrupt processing can defer the high priority interrupt and result in the jitter in that interrupt response. Fix is to raise the priority of the high priority interrupt above the priority of the SVCALL interrupt. Suggested by Nathan Hartman.

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This commit is contained in:
Gregory Nutt 2019-08-09 07:07:16 -06:00
parent 72f56baafd
commit c300f27130
1 changed files with 14 additions and 1 deletions
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15
arch/arm/include/armv7-m/nvicpri.h
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@ -86,13 +86,26 @@
*/
#if defined(CONFIG_ARCH_HIPRI_INTERRUPT) && defined(CONFIG_ARCH_INT_DISABLEALL)
/* In this case, disabling interrupts will disable all interrupts EXCEPT
* SVCALL. NOTE that this will add jitter to the high priority interrupt
* response because it may be deferred by SVCALL interupt handling.
*/
# define NVIC_SYSH_MAXNORMAL_PRIORITY NVIC_SYSH_PRIORITY_DEFAULT
# define NVIC_SYSH_HIGH_PRIORITY (NVIC_SYSH_PRIORITY_DEFAULT - 1*NVIC_SYSH_PRIORITY_STEP)
# define NVIC_SYSH_DISABLE_PRIORITY (NVIC_SYSH_PRIORITY_DEFAULT - 1*NVIC_SYSH_PRIORITY_STEP)
# define NVIC_SYSH_SVCALL_PRIORITY (NVIC_SYSH_PRIORITY_DEFAULT - 2*NVIC_SYSH_PRIORITY_STEP)
#else
/* In this case, the high priority interrupt must be highest priority. This
* prevents SVCALL handling from adding jitter to high priority interrupt
* response. Disabling interrupts will disable all interrupts EXCEPT SVCALL
* and the high priority interrupts.
*/
# define NVIC_SYSH_MAXNORMAL_PRIORITY NVIC_SYSH_PRIORITY_DEFAULT
# define NVIC_SYSH_HIGH_PRIORITY (NVIC_SYSH_PRIORITY_DEFAULT - 1*NVIC_SYSH_PRIORITY_STEP)
# define NVIC_SYSH_HIGH_PRIORITY (NVIC_SYSH_PRIORITY_DEFAULT - 2*NVIC_SYSH_PRIORITY_STEP)
# define NVIC_SYSH_DISABLE_PRIORITY NVIC_SYSH_PRIORITY_DEFAULT
# define NVIC_SYSH_SVCALL_PRIORITY (NVIC_SYSH_PRIORITY_DEFAULT - 1*NVIC_SYSH_PRIORITY_STEP)
#endif