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Commit 532f07ca authored by Mike Frysinger's avatar Mike Frysinger
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Blackfin: fix early_dma_memcpy() handling of busy channels 



The early logic to locate a free DMA channel and then set it up was broken
in a few ways that only manifested itself when we needed to set up more
than 2 on chip SRAM regions (most board defaults setup 1 or 2).  First, we
checked the wrong status register (the destination gets updated, not the
source) and second, we did the ssync before rather than after resetting a
DMA config register.

Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
parent fb4b5d3a

arch/blackfin/kernel/bfin_dma_5xx.c

+14 −15
Original line number Diff line number Diff line
@@ -253,32 +253,31 @@ void __init early_dma_memcpy(void *pdst, const void *psrc, size_t size) 
	BUG_ON(src % 4);

	BUG_ON(size % 4);



	/* Force a sync in case a previous config reset on this channel

	 * occurred.  This is needed so subsequent writes to DMA registers

	 * are not spuriously lost/corrupted.

	 */

	__builtin_bfin_ssync();



	src_ch = 0;

	/* Find an avalible memDMA channel */

	while (1) {

		if (!src_ch || src_ch == (struct dma_register *)MDMA_S1_NEXT_DESC_PTR) {

			dst_ch = (struct dma_register *)MDMA_D0_NEXT_DESC_PTR;

			src_ch = (struct dma_register *)MDMA_S0_NEXT_DESC_PTR;

		} else {

		if (src_ch == (struct dma_register *)MDMA_S0_NEXT_DESC_PTR) {

			dst_ch = (struct dma_register *)MDMA_D1_NEXT_DESC_PTR;

			src_ch = (struct dma_register *)MDMA_S1_NEXT_DESC_PTR;

		} else {

			dst_ch = (struct dma_register *)MDMA_D0_NEXT_DESC_PTR;

			src_ch = (struct dma_register *)MDMA_S0_NEXT_DESC_PTR;

		}



		if (!bfin_read16(&src_ch->cfg)) {

		if (!bfin_read16(&src_ch->cfg))

			break;

		} else {

			if (bfin_read16(&src_ch->irq_status) & DMA_DONE)

		else if (bfin_read16(&dst_ch->irq_status) & DMA_DONE) {

			bfin_write16(&src_ch->cfg, 0);

			break;

		}



	}



	/* Force a sync in case a previous config reset on this channel

	 * occurred.  This is needed so subsequent writes to DMA registers

	 * are not spuriously lost/corrupted.

	 */

	__builtin_bfin_ssync();



	/* Destination */

	bfin_write32(&dst_ch->start_addr, dst);

	bfin_write16(&dst_ch->x_count, size >> 2);