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Commit 99532559 authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Russell King
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[ARM] 3500/1: fix PXA27x DMA allocation priority 



Patch from Nicolas Pitre

Intel PXA27x developers manual section 5.4.1.1 lists a priority
distribution for the DMA channels differently than what the code
currently assumes.  This patch fixes that.

Noticed by Simon Vogl <vogl@soft.uni-linz.ac.at>

Signed-off-by: default avatarNicolas Pitre <nico@cam.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent b7d7ef87

arch/arm/mach-pxa/dma.c

+5 −12
Original line number Diff line number Diff line
@@ -45,23 +45,16 @@ int pxa_request_dma (char *name, pxa_dma_prio prio, 


	local_irq_save(flags);



	do {

		/* try grabbing a DMA channel with the requested priority */

	for (i = prio; i < prio + PXA_DMA_NBCH(prio); i++) {

		pxa_for_each_dma_prio (i, prio) {

			if (!dma_channels[i].name) {

				found = 1;

				break;

			}

		}



	if (!found) {

		/* requested prio group is full, try hier priorities */

		for (i = prio-1; i >= 0; i--) {

			if (!dma_channels[i].name) {

				found = 1;

				break;

			}

		}

	}

		/* if requested prio group is full, try a hier priority */

	} while (!found && prio--);



	if (found) {

		DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;

include/asm-arm/arch-pxa/dma.h

+14 −12
Original line number Diff line number Diff line
@@ -24,27 +24,29 @@ typedef struct pxa_dma_desc { 
	volatile u32 dcmd;	/* DCMD value for the current transfer */

} pxa_dma_desc;



typedef enum {

	DMA_PRIO_HIGH = 0,

	DMA_PRIO_MEDIUM = 1,

	DMA_PRIO_LOW = 2

} pxa_dma_prio;



#if defined(CONFIG_PXA27x)



#define PXA_DMA_CHANNELS	32

#define PXA_DMA_NBCH(prio)	((prio == DMA_PRIO_LOW) ? 16 : 8)



typedef enum {

	DMA_PRIO_HIGH = 0,

	DMA_PRIO_MEDIUM = 8,

	DMA_PRIO_LOW = 16

} pxa_dma_prio;

#define pxa_for_each_dma_prio(ch, prio)					\

for (									\

	ch = prio * 4;							\

	ch != (4 << prio) + 16;						\

	ch = (ch + 1 == (4 << prio)) ? (prio * 4 + 16) : (ch + 1)	\

)



#elif defined(CONFIG_PXA25x)



#define PXA_DMA_CHANNELS	16

#define PXA_DMA_NBCH(prio)	((prio == DMA_PRIO_LOW) ? 8 : 4)



typedef enum {

	DMA_PRIO_HIGH = 0,

	DMA_PRIO_MEDIUM = 4,

	DMA_PRIO_LOW = 8

} pxa_dma_prio;

#define pxa_for_each_dma_prio(ch, prio)					\

	for (ch = prio * 4; ch != (4 << prio); ch++)



#endif