Blackfin: dma_memcpy(): fix random failures

We have to make sure the DMA channel is actually disabled in hardware before
attempting to reprogram it.  Otherwise the new settings are ignored and we
end up with random hangs/failures.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

lib_blackfin/string.c

@@ -136,6 +136,14 @@ int strncmp(const char *cs, const char *ct, size_t count)
  */
 void dma_memcpy_nocache(void *dst, const void *src, size_t count)
 {
+	/* Disable DMA in case it's still running (older u-boot's did not
+	 * always turn them off).  Do it before the if statement below so
+	 * we can be cheap and not do a SSYNC() due to the forced abort.
+	 */
+	bfin_write_MDMA_D0_CONFIG(0);
+	bfin_write_MDMA_S0_CONFIG(0);
+	bfin_write_MDMA_D0_IRQ_STATUS(DMA_RUN | DMA_DONE | DMA_ERR);
+
 	/* Scratchpad cannot be a DMA source or destination */
 	if (((unsigned long)src >= L1_SRAM_SCRATCH &&
 	     (unsigned long)src < L1_SRAM_SCRATCH_END) ||
@@ -143,10 +151,6 @@ void dma_memcpy_nocache(void *dst, const void *src, size_t count)
 	     (unsigned long)dst < L1_SRAM_SCRATCH_END))
 		hang();
 
-	bfin_write_MDMA_S0_CONFIG(0);
-	bfin_write_MDMA_D0_CONFIG(0);
-	bfin_write_MDMA_D0_IRQ_STATUS(DMA_RUN | DMA_DONE | DMA_ERR);
-
 	/* Copy sram functions from sdram to sram */
 	/* Setup destination start address */
 	bfin_write_MDMA_D0_START_ADDR(dst);
@@ -164,14 +168,13 @@ void dma_memcpy_nocache(void *dst, const void *src, size_t count)
 
 	/* Enable source DMA */
 	bfin_write_MDMA_S0_CONFIG(DMAEN);
-
-	bfin_write_MDMA_D0_CONFIG(WNR | DMAEN);
+	bfin_write_MDMA_D0_CONFIG(WNR | DMAEN | DI_EN);
 	SSYNC();
 
-	while (bfin_read_MDMA_D0_IRQ_STATUS() & DMA_RUN)
+	while (!(bfin_read_MDMA_D0_IRQ_STATUS() & DMA_DONE))
 		continue;
 
-	bfin_write_MDMA_D0_IRQ_STATUS(bfin_read_MDMA_D0_IRQ_STATUS() | DMA_RUN | DMA_DONE | DMA_ERR);
+	bfin_write_MDMA_D0_IRQ_STATUS(DMA_RUN | DMA_DONE | DMA_ERR);
 	bfin_write_MDMA_D0_CONFIG(0);
 	bfin_write_MDMA_S0_CONFIG(0);
 }