From: Peter Ujfalusi Date: Fri, 9 Dec 2011 21:38:00 +0000 (-0800) Subject: ARM: OMAP2+: DMA: Workaround for invalid destination position X-Git-Tag: firefly_0821_release~3680^2~3797^2~3^2^2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=06e8077b556a372871c04dd68f47e8c25e9ca348;p=firefly-linux-kernel-4.4.55.git ARM: OMAP2+: DMA: Workaround for invalid destination position 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 Reviewed-by: Jarkko Nikula Signed-off-by: Tony Lindgren --- diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c index a9983b695a18..002fb4d96bbc 100644 --- a/arch/arm/plat-omap/dma.c +++ b/arch/arm/plat-omap/dma.c @@ -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);