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stmhal: Increase the priority of UART IRQ. 

The UARTs have no FIFOs, so if interrupts are disabled
for more than a character time (10 usec at 1 Mbit/sec)
then characters get dropped.

The overhead for handling a UART ISR is about 0.5 usec,
so even at baud rates of 1 Mbit/sec this only corresponds
to about 5% of the CPU. Lower baud rates will have less
of an impact.
This commit is contained in:
Dave Hylands 2015-11-24 10:22:30 -08:00 committed by Damien George
parent 90202b4c0d
commit c8437f97ae
1 changed files with 6 additions and 4 deletions
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10
stmhal/irq.h
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@ -64,9 +64,14 @@ MP_DECLARE_CONST_FUN_OBJ(pyb_enable_irq_obj);
//#def IRQ_PRI_SYSTICK 0
//#def IRQ_SUBPRI_SYSTICK 0
// The UARTs have no FIFOs, so if they don't get serviced quickly then characters
// get dropped. The handling for each character only consumes about 0.5 usec
#define IRQ_PRI_UART 1
#define IRQ_SUBPRI_UART 0
// Flash IRQ must be higher priority than interrupts of all those components
// that rely on the flash storage.
#define IRQ_PRI_FLASH 1
#define IRQ_PRI_FLASH 2
#define IRQ_SUBPRI_FLASH 0
// SDIO must be higher priority than DMA for SDIO DMA transfers to work.
@ -93,9 +98,6 @@ MP_DECLARE_CONST_FUN_OBJ(pyb_enable_irq_obj);
#define IRQ_PRI_CAN 7
#define IRQ_SUBPRI_CAN 0
#define IRQ_PRI_UART 13
#define IRQ_SUBPRI_UART 0
// Interrupt priority for non-special timers.
#define IRQ_PRI_TIMX 14
#define IRQ_SUBPRI_TIMX 0