esp: remove dma_counter from ESPState

The value of dma_counter is set once at the start of the transfer and remains
the same until the transfer is complete. This allows the check in esp_transfer_data
to be simplified since dma_left will always be non-zero until the transfer is
completed.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20210304221103.6369-13-mark.cave-ayland@ilande.co.uk>

hw/scsi/esp.c

@@ -229,7 +229,6 @@ static void do_busid_cmd(ESPState *s, uint8_t *buf, uint8_t busid)
     if (datalen != 0) {
         s->rregs[ESP_RSTAT] = STAT_TC;
         s->dma_left = 0;
-        s->dma_counter = 0;
         if (datalen > 0) {
             s->rregs[ESP_RSTAT] |= STAT_DI;
         } else {
@@ -542,7 +541,7 @@ void esp_transfer_data(SCSIRequest *req, uint32_t len)
     s->async_buf = scsi_req_get_buf(req);
     if (s->dma_left) {
         esp_do_dma(s);
-    } else if (s->dma_counter != 0 && s->ti_size <= 0) {
+    } else if (s->ti_size <= 0) {
         /*
          * If this was the last part of a DMA transfer then the
          * completion interrupt is deferred to here.
@@ -561,7 +560,6 @@ static void handle_ti(ESPState *s)
     }
 
     dmalen = esp_get_tc(s);
-    s->dma_counter = dmalen;
 
     if (s->do_cmd) {
         minlen = (dmalen < ESP_CMDBUF_SZ) ? dmalen : ESP_CMDBUF_SZ;

include/hw/scsi/esp.h

@@ -50,9 +50,6 @@ struct ESPState {
 
     /* The amount of data left in the current DMA transfer.  */
     uint32_t dma_left;
-    /* The size of the current DMA transfer.  Zero if no transfer is in
-       progress.  */
-    uint32_t dma_counter;
     int dma_enabled;
 
     uint32_t async_len;