From 71ca3a134916c74bb9199d1da0941a77670c914a Mon Sep 17 00:00:00 2001 From: Bohdan Tymkiv Date: Thu, 2 Dec 2021 10:08:33 +0200 Subject: [PATCH] target/arm_jtag.h: fix wrong comparison in arm_jtag_set_instr Change [1] introduced a regression that results in comparison in arm_jtag_set_instr() to be always true if the length of the IR register is not 8 bit. The value on the left side of the != operator contains only tap->ir_length number of bits while value on the right is full 8-bit instruction code. This forces OpenOCD to update the JTAG IR register on each transaction even if the instruction in the JTAG IR register is correct. This causes noticeable performance degradation, especially with slow JTAG adapters. [1] https://review.openocd.org/c/openocd/+/6285 time ./src/openocd -s tcl/ -f interface/cmsis-dap.cfg \ -c "transport select jtag" -f target/psoc6.cfg \ -c "init; load_image data.bin 0x08000000; exit" Without this change: real 0m4,863s user 0m0,074s sys 0m0,128s With this change: real 0m3,083s user 0m0,038s sys 0m0,098s Signed-off-by: Bohdan Tymkiv Change-Id: Iaded83a04ecc7e65f18256afae582267ccc1fc59 Reviewed-on: https://review.openocd.org/c/openocd/+/6762 Tested-by: jenkins Reviewed-by: Tomas Vanek Reviewed-by: Antonio Borneo --- src/target/arm_jtag.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/target/arm_jtag.h b/src/target/arm_jtag.h index bf5b837486..f3e0bc2a3d 100644 --- a/src/target/arm_jtag.h +++ b/src/target/arm_jtag.h @@ -23,6 +23,7 @@ #define OPENOCD_TARGET_ARM_JTAG_H #include +#include struct arm_jtag { struct jtag_tap *tap; @@ -42,7 +43,7 @@ static inline int arm_jtag_set_instr(struct jtag_tap *tap, uint32_t new_instr, void *no_verify_capture, tap_state_t end_state) { /* inline most common code path */ - if (buf_get_u32(tap->cur_instr, 0, tap->ir_length) != new_instr) + if (buf_get_u32(tap->cur_instr, 0, tap->ir_length) != (new_instr & (BIT(tap->ir_length) - 1))) return arm_jtag_set_instr_inner(tap, new_instr, no_verify_capture, end_state); return ERROR_OK; -- 2.30.2