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ARM: OMAP2+: DMA: Workaround for invalid destination position

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If the DMA destination position has been asked before the
first actual data transfer has been done, the CDAC
register still contains 0 (it is initialized to 0 at
omsp_dma_start).
If CDAC == 0, return the programmed start address.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This commit is contained in:
Peter Ujfalusi 2011-12-09 13:38:00 -08:00 committed by Tony Lindgren
parent 7ba966804f
commit 06e8077b55
1 changed files with 9 additions and 1 deletions
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10
arch/arm/plat-omap/dma.c
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@ -1074,8 +1074,16 @@ dma_addr_t omap_get_dma_dst_pos(int lch)
* omap 3.2/3.3 erratum: sometimes 0 is returned if CSAC/CDAC is
* read before the DMA controller finished disabling the channel.
*/
if (!cpu_is_omap15xx() && offset == 0)
if (!cpu_is_omap15xx() && offset == 0) {
offset = p->dma_read(CDAC, lch);
/*
* CDAC == 0 indicates that the DMA transfer on the channel has
* not been started (no data has been transferred so far).
* Return the programmed destination start address in this case.
*/
if (unlikely(!offset))
offset = p->dma_read(CDSA, lch);
}
if (cpu_class_is_omap1())
offset |= (p->dma_read(CDSA, lch) & 0xFFFF0000);