From: Daniel Glöckner Date: Wed, 4 Oct 2017 21:07:53 +0000 (+0200) Subject: usb_blaster: Don't unnecessarily go through DR-/IR-Pause X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=e57f8e12da6da02c192cd9365185fe8eee46b080;p=openocd usb_blaster: Don't unnecessarily go through DR-/IR-Pause There is no need to pass through DR-/IR-Pause after a scan if we want to go to DR-/IR-Update. We just have to skip the first step of the path to the end state because we already did that step when shifting the last bit. v2: - Fix comments as remarked in review of v1 Change-Id: I3c10f02794b2233f63d2150934e2768430873caa Signed-off-by: Daniel Glöckner Reviewed-on: http://openocd.zylin.com/4245 Tested-by: jenkins Reviewed-by: Christopher Head Reviewed-by: Matthias Welwarsky --- diff --git a/src/jtag/drivers/usb_blaster/usb_blaster.c b/src/jtag/drivers/usb_blaster/usb_blaster.c index df9f2a17..8ccf8717 100644 --- a/src/jtag/drivers/usb_blaster/usb_blaster.c +++ b/src/jtag/drivers/usb_blaster/usb_blaster.c @@ -445,6 +445,7 @@ static void ublast_queue_bytes(uint8_t *bytes, int nb_bytes) * ublast_tms_seq - write a TMS sequence transition to JTAG * @bits: TMS bits to be written (bit0, bit1 .. bitN) * @nb_bits: number of TMS bits (between 1 and 8) + * @skip: number of TMS bits to skip at the beginning of the series * * Write a serie of TMS transitions, where each transition consists in : * - writing out TCK=0, TMS=, TDI= @@ -452,12 +453,12 @@ static void ublast_queue_bytes(uint8_t *bytes, int nb_bytes) * The function ensures that at the end of the sequence, the clock (TCK) is put * low. */ -static void ublast_tms_seq(const uint8_t *bits, int nb_bits) +static void ublast_tms_seq(const uint8_t *bits, int nb_bits, int skip) { int i; DEBUG_JTAG_IO("(bits=%02x..., nb_bits=%d)", bits[0], nb_bits); - for (i = 0; i < nb_bits; i++) + for (i = skip; i < nb_bits; i++) ublast_clock_tms((bits[i / 8] >> (i % 8)) & 0x01); ublast_idle_clock(); } @@ -469,7 +470,7 @@ static void ublast_tms_seq(const uint8_t *bits, int nb_bits) static void ublast_tms(struct tms_command *cmd) { DEBUG_JTAG_IO("(num_bits=%d)", cmd->num_bits); - ublast_tms_seq(cmd->bits, cmd->num_bits); + ublast_tms_seq(cmd->bits, cmd->num_bits, 0); } /** @@ -501,11 +502,12 @@ static void ublast_path_move(struct pathmove_command *cmd) /** * ublast_state_move - move JTAG state to the target state * @state: the target state + * @skip: number of bits to skip at the beginning of the path * * Input the correct TMS sequence to the JTAG TAP so that we end up in the * target state. This assumes the current state (tap_get_state()) is correct. */ -static void ublast_state_move(tap_state_t state) +static void ublast_state_move(tap_state_t state, int skip) { uint8_t tms_scan; int tms_len; @@ -516,7 +518,7 @@ static void ublast_state_move(tap_state_t state) return; tms_scan = tap_get_tms_path(tap_get_state(), state); tms_len = tap_get_tms_path_len(tap_get_state(), state); - ublast_tms_seq(&tms_scan, tms_len); + ublast_tms_seq(&tms_scan, tms_len, skip); tap_set_state(state); } @@ -688,9 +690,9 @@ static void ublast_runtest(int cycles, tap_state_t state) { DEBUG_JTAG_IO("%s(cycles=%i, end_state=%d)", __func__, cycles, state); - ublast_state_move(TAP_IDLE); + ublast_state_move(TAP_IDLE, 0); ublast_queue_tdi(NULL, cycles, SCAN_OUT); - ublast_state_move(state); + ublast_state_move(state, 0); } static void ublast_stableclocks(int cycles) @@ -720,9 +722,9 @@ static int ublast_scan(struct scan_command *cmd) scan_bits = jtag_build_buffer(cmd, &buf); if (cmd->ir_scan) - ublast_state_move(TAP_IRSHIFT); + ublast_state_move(TAP_IRSHIFT, 0); else - ublast_state_move(TAP_DRSHIFT); + ublast_state_move(TAP_DRSHIFT, 0); log_buf = hexdump(buf, DIV_ROUND_UP(scan_bits, 8)); DEBUG_JTAG_IO("%s(scan=%s, type=%s, bits=%d, buf=[%s], end_state=%d)", __func__, @@ -733,20 +735,15 @@ static int ublast_scan(struct scan_command *cmd) ublast_queue_tdi(buf, scan_bits, type); - /* - * As our JTAG is in an unstable state (IREXIT1 or DREXIT1), move it - * forward to a stable IRPAUSE or DRPAUSE. - */ - ublast_clock_tms(0); - if (cmd->ir_scan) - tap_set_state(TAP_IRPAUSE); - else - tap_set_state(TAP_DRPAUSE); - ret = jtag_read_buffer(buf, cmd); if (buf) free(buf); - ublast_state_move(cmd->end_state); + /* + * ublast_queue_tdi sends the last bit with TMS=1. We are therefore + * already in Exit1-DR/IR and have to skip the first step on our way + * to end_state. + */ + ublast_state_move(cmd->end_state, 1); return ret; } @@ -776,7 +773,7 @@ static void ublast_initial_wipeout(void) /* * Put JTAG in RESET state (five 1 on TMS) */ - ublast_tms_seq(&tms_reset, 5); + ublast_tms_seq(&tms_reset, 5, 0); tap_set_state(TAP_RESET); } @@ -805,7 +802,7 @@ static int ublast_execute_queue(void) ublast_stableclocks(cmd->cmd.stableclocks->num_cycles); break; case JTAG_TLR_RESET: - ublast_state_move(cmd->cmd.statemove->end_state); + ublast_state_move(cmd->cmd.statemove->end_state, 0); break; case JTAG_PATHMOVE: ublast_path_move(cmd->cmd.pathmove);