esp.c: move esp_select() to ESP selection commands from get_cmd()

Since the DREQ value depends upon the result of the selection process, add a
workaround to each esp_select() to manually assert DREQ durring the MESSAGE OUT
and COMMAND phases.

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: <20240112125420.514425-6-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

hw/scsi/esp.c

@@ -263,10 +263,6 @@ static uint32_t get_cmd(ESPState *s, uint32_t maxlen)
             dmalen = MIN(fifo8_num_free(&s->cmdfifo), dmalen);
             fifo8_push_all(&s->cmdfifo, buf, dmalen);
         } else {
-            if (esp_select(s) < 0) {
-                return -1;
-            }
-            esp_raise_drq(s);
             return 0;
         }
     } else {
@@ -280,9 +276,6 @@ static uint32_t get_cmd(ESPState *s, uint32_t maxlen)
     }
     trace_esp_get_cmd(dmalen, target);
 
-    if (esp_select(s) < 0) {
-        return -1;
-    }
     return dmalen;
 }
 
@@ -380,12 +373,18 @@ static void handle_satn(ESPState *s)
         return;
     }
     esp_set_pdma_cb(s, SATN_PDMA_CB);
+    if (esp_select(s) < 0) {
+        return;
+    }
     cmdlen = get_cmd(s, ESP_CMDFIFO_SZ);
     if (cmdlen > 0) {
         s->cmdfifo_cdb_offset = 1;
         s->do_cmd = 0;
         do_cmd(s);
     } else if (cmdlen == 0) {
+        if (s->dma) {
+            esp_raise_drq(s);
+        }
         s->do_cmd = 1;
         /* Target present, but no cmd yet - switch to command phase */
         s->rregs[ESP_RSEQ] = SEQ_CD;
@@ -411,12 +410,18 @@ static void handle_s_without_atn(ESPState *s)
         return;
     }
     esp_set_pdma_cb(s, S_WITHOUT_SATN_PDMA_CB);
+    if (esp_select(s) < 0) {
+        return;
+    }
     cmdlen = get_cmd(s, ESP_CMDFIFO_SZ);
     if (cmdlen > 0) {
         s->cmdfifo_cdb_offset = 0;
         s->do_cmd = 0;
         do_cmd(s);
     } else if (cmdlen == 0) {
+        if (s->dma) {
+            esp_raise_drq(s);
+        }
         s->do_cmd = 1;
         /* Target present, but no cmd yet - switch to command phase */
         s->rregs[ESP_RSEQ] = SEQ_CD;
@@ -446,6 +451,9 @@ static void handle_satn_stop(ESPState *s)
         return;
     }
     esp_set_pdma_cb(s, SATN_STOP_PDMA_CB);
+    if (esp_select(s) < 0) {
+        return;
+    }
     cmdlen = get_cmd(s, 1);
     if (cmdlen > 0) {
         trace_esp_handle_satn_stop(fifo8_num_used(&s->cmdfifo));
@@ -456,6 +464,9 @@ static void handle_satn_stop(ESPState *s)
         s->rregs[ESP_RSEQ] = SEQ_MO;
         esp_raise_irq(s);
     } else if (cmdlen == 0) {
+        if (s->dma) {
+            esp_raise_drq(s);
+        }
         s->do_cmd = 1;
         /* Target present, switch to message out phase */
         s->rregs[ESP_RSEQ] = SEQ_MO;