* Peter Ujfalusi <[email protected]> [111031 06:46]: > If the DMA source position has been asked before the > first actual data transfer has been done, the CSAC > register does not contain valid information. > We can identify this situation by checking the CDAC > register: > CDAC != 0 indicates that the DMA transfer on the channel has > been started already. > When CDAC == 0 we can not trust the CSAC value since it has > not been updated, and can contain random number. > Return the start address in case the DMA has not jet started. > > Note: The CDAC register has been initialized to 0 at dma_start > time. > > Signed-off-by: Peter Ujfalusi <[email protected]> > --- > arch/arm/plat-omap/dma.c | 15 +++++++++++++-- > 1 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c > index c22217c..38b0d44 100644 > --- a/arch/arm/plat-omap/dma.c > +++ b/arch/arm/plat-omap/dma.c > @@ -1024,12 +1024,23 @@ EXPORT_SYMBOL(omap_set_dma_callback); > */ > dma_addr_t omap_get_dma_src_pos(int lch) > { > + u32 cdac; > dma_addr_t offset = 0; > > if (cpu_is_omap15xx()) > offset = p->dma_read(CPC, lch); > - else > - offset = p->dma_read(CSAC, lch); > + else { > + /* > + * CDAC == 0 indicates that the DMA transfer on the channel has > + * not been started (no data has been transferred so far). > + * Return the programmed source start address in this case. > + */ > + cdac = p->dma_read(CDAC, lch); > + if (likely(cdac)) > + offset = p->dma_read(CSAC, lch); > + else > + offset = p->dma_read(CSSA, lch); > + } > > if (IS_DMA_ERRATA(DMA_ERRATA_3_3) && offset == 0) > offset = p->dma_read(CSAC, lch);
Should these tests be done only after the errata re-read for both src and dst patches? Otherwise the errata will not be handled? Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
