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Commit e659587c authored by Russell King's avatar Russell King
Browse files

ARM: riscpc: dma: improve address/length writing 



Rearrange writing the DMA addresses to generate more efficient code.

Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
parent 39694ed0

arch/arm/mach-rpc/dma.c

+11 −15
Original line number Diff line number Diff line
@@ -100,7 +100,7 @@ static irqreturn_t iomd_dma_handle(int irq, void *dev_id) 
	struct iomd_dma *idma = dev_id;

	unsigned long base = idma->base;

	unsigned int state = idma->state;

	unsigned int status;

	unsigned int status, cur, end;



	do {

		status = iomd_readb(base + ST);
@@ -110,21 +110,17 @@ static irqreturn_t iomd_dma_handle(int irq, void *dev_id) 
		if ((state ^ status) & DMA_ST_AB)

			iomd_get_next_sg(idma);



		switch (status & (DMA_ST_OFL | DMA_ST_AB)) {

		case DMA_ST_OFL:			/* OIA */

		case DMA_ST_AB:				/* .IB */

			iomd_writel(idma->cur_addr, base + CURA);

			iomd_writel(idma->cur_len, base + ENDA);

			state = DMA_ST_AB;

			break;



		case DMA_ST_OFL | DMA_ST_AB:		/* OIB */

		case 0:					/* .IA */

			iomd_writel(idma->cur_addr, base + CURB);

			iomd_writel(idma->cur_len, base + ENDB);

			state = 0;

			break;

		// This efficiently implements state = OFL != AB ? AB : 0

		state = ((status >> 2) ^ status) & DMA_ST_AB;

		if (state) {

			cur = CURA;

			end = ENDA;

		} else {

			cur = CURB;

			end = ENDB;

		}

		iomd_writel(idma->cur_addr, base + cur);

		iomd_writel(idma->cur_len, base + end);



		if (status & DMA_ST_OFL &&

		    idma->cur_len == (DMA_END_S|DMA_END_L))