[PATCH 34/88] esp.c: update esp_do_dma() bypass if async_len is zero to include non-zero transfer check

[Mark Cave-Ayland]

In the PDMA case the last transfer from the device to the FIFO has occurred
(async_len is zero) but esp_do_dma() is still being called to drain the
remaining FIFO contents.

The additional non-zero transfer check ensures that we still defer the SCSI
layer in the case where we are waiting for data for a TI command or a DMA
enable signal.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 hw/scsi/esp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 14284ef54a..9647be4cc3 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -696,7 +696,7 @@ static void esp_do_dma(ESPState *s)
     if (!s->current_req) {
         return;
     }
-    if (s->async_len == 0) {
+    if (s->async_len == 0 && esp_get_tc(s) && s->ti_size) {
         /* Defer until data is available.  */
         return;
     }
-- 
2.39.2