The contents of the FIFO should only be copied to cmdfifo for ESP commands that
are sending data to the SCSI bus, which are the SEL_* commands and the TI
command. Otherwise any incoming data should be held in the FIFO as normal.

This fixes booting of NetBSD m68k under the Q800 machine once again.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Helge Deller <deller@gmx.de>
Tested-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20240112125420.514425-78-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 hw/scsi/esp.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 17e2db442c..d63039af89 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -712,14 +712,13 @@ static void esp_do_nodma(ESPState *s)
 
     switch (esp_get_phase(s)) {
     case STAT_MO:
-        /* Copy FIFO into cmdfifo */
-        n = esp_fifo_pop_buf(&s->fifo, buf, fifo8_num_used(&s->fifo));
-        n = MIN(fifo8_num_free(&s->cmdfifo), n);
-        fifo8_push_all(&s->cmdfifo, buf, n);
-        s->cmdfifo_cdb_offset += n;
-
         switch (s->rregs[ESP_CMD]) {
         case CMD_SELATN:
+            /* Copy FIFO into cmdfifo */
+            n = esp_fifo_pop_buf(&s->fifo, buf, fifo8_num_used(&s->fifo));
+            n = MIN(fifo8_num_free(&s->cmdfifo), n);
+            fifo8_push_all(&s->cmdfifo, buf, n);
+
             if (fifo8_num_used(&s->cmdfifo) >= 1) {
                 /* First byte received, switch to command phase */
                 esp_set_phase(s, STAT_CD);
@@ -734,6 +733,11 @@ static void esp_do_nodma(ESPState *s)
             break;
 
         case CMD_SELATNS:
+            /* Copy one byte from FIFO into cmdfifo */
+            n = esp_fifo_pop_buf(&s->fifo, buf, 1);
+            n = MIN(fifo8_num_free(&s->cmdfifo), n);
+            fifo8_push_all(&s->cmdfifo, buf, n);
+
             if (fifo8_num_used(&s->cmdfifo) >= 1) {
                 /* First byte received, stop in message out phase */
                 s->rregs[ESP_RSEQ] = SEQ_MO;
@@ -746,6 +750,11 @@ static void esp_do_nodma(ESPState *s)
             break;
 
         case CMD_TI:
+            /* Copy FIFO into cmdfifo */
+            n = esp_fifo_pop_buf(&s->fifo, buf, fifo8_num_used(&s->fifo));
+            n = MIN(fifo8_num_free(&s->cmdfifo), n);
+            fifo8_push_all(&s->cmdfifo, buf, n);
+
             /* ATN remains asserted until FIFO empty */
             s->cmdfifo_cdb_offset = fifo8_num_used(&s->cmdfifo);
             esp_set_phase(s, STAT_CD);
-- 
2.39.2