bcm2835_dma: Re-initialize xlen in TD mode

TD (two dimensions) DMA mode did not work, because the xlen variable
has not been re-initialized before each additional ylen run through
in bcm2835_dma_update(). Fix it.

Signed-off-by: Rene Stange <rsta2@o2online.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/dma/bcm2835_dma.c

@@ -54,7 +54,7 @@
 static void bcm2835_dma_update(BCM2835DMAState *s, unsigned c)
 {
     BCM2835DMAChan *ch = &s->chan[c];
-    uint32_t data, xlen, ylen;
+    uint32_t data, xlen, xlen_td, ylen;
     int16_t dst_stride, src_stride;
 
     if (!(s->enable & (1 << c))) {
@@ -82,6 +82,7 @@ static void bcm2835_dma_update(BCM2835DMAState *s, unsigned c)
             dst_stride = 0;
             src_stride = 0;
         }
+        xlen_td = xlen;
 
         while (ylen != 0) {
             /* Normal transfer mode */
@@ -117,6 +118,7 @@ static void bcm2835_dma_update(BCM2835DMAState *s, unsigned c)
             if (--ylen != 0) {
                 ch->source_ad += src_stride;
                 ch->dest_ad += dst_stride;
+                xlen = xlen_td;
             }
         }
         ch->cs |= BCM2708_DMA_END;