[SeaBIOS] [PATCH v3 3/3] esp-scsi: handle non-DMA SCSI commands with no data phase

[Mark Cave-Ayland]

The existing esp-scsi state machine checks for the STAT_TC bit to exit state 1
but in the case where there is no data phase, a non-DMA command is executed
which doesn't set STAT_TC. This only works because QEMU currently always sets
STAT_TC just after issuing every SCSI command.

Update the esp-scsi state machine so that in the case where there is no data
phase, we immediately execute CMD_ICCS instead of waiting for STAT_TC to be
set which will never happen with a non-DMA CMD_SELATN command.

Signed-off-by: Mark Cave-Ayland 
---
 src/hw/esp-scsi.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/hw/esp-scsi.c b/src/hw/esp-scsi.c
index ebdbd02..f19804f 100644
--- a/src/hw/esp-scsi.c
+++ b/src/hw/esp-scsi.c
@@ -137,19 +137,28 @@ esp_scsi_process_op(struct disk_op_s *op)
                     esp_scsi_dma(iobase, (u32)op->buf_fl, count, scsi_is_read(op));
                     outb(ESP_CMD_TI | ESP_CMD_DMA, iobase + ESP_CMD);
                     continue;
+                } else {
+                    /* No data phase.  */
+                    state++;
                 }
             }
         }

/* At end of DMA TC is set again -> complete command.  */
         if (state == 1 && (stat & ESP_STAT_TC)) {
+            state++;
+            continue;
+        }
+
+        /* Request message in data.  */
+        if (state == 2) {
             state++;
             outb(ESP_CMD_ICCS, iobase + ESP_CMD);
             continue;
         }

/* Finally read data from the message in phase.  */
-        if (state == 2 && (stat & ESP_STAT_MSG)) {
+        if (state == 3 && (stat & ESP_STAT_MSG)) {
             state++;
             status = inb(iobase + ESP_FIFO);
             inb(iobase + ESP_FIFO);