On Mon, 4 Oct 2010 14:44:28 +0530 "G, Manjunath Kondaiah" <manjugk@xxxxxx> wrote: > > > > -----Original Message----- > > From: linux-omap-owner@xxxxxxxxxxxxxxx > > [mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of Peter Ujfalusi > > Sent: Monday, October 04, 2010 1:48 PM > > To: Tony Lindgren > > Cc: linux-omap@xxxxxxxxxxxxxxx; Jarkko Nikula; > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > > Subject: [PATCH v4 1/4] omap: dma: Fix buffering disable bit > > setting for omap24xx > > > > From: ext Jarkko Nikula <jhnikula@xxxxxxxxx> > > > > An errata workaround for omap24xx is not setting the > > buffering disable bit > > 25 what is the purpose but channel enable bit 7 instead. > > ... > > > diff --git a/arch/arm/plat-omap/dma.c > > b/arch/arm/plat-omap/dma.c index ec7eddf..6914ccf 100644 > > --- a/arch/arm/plat-omap/dma.c > > +++ b/arch/arm/plat-omap/dma.c > > @@ -999,8 +999,9 @@ void omap_start_dma(int lch) > > * Errata: On ES2.0 BUFFERING disable must be set. > > * This will always fail on ES1.0 > > */ > > Sorry, I didn't catch this with earlier patch. > > Looks like wrong comment. only on 2430ES1.0 and for all omap2420, > buffer disable should be set. > I feel below description will be useful to the reader: > "Errata: Inter Frame DMA buffering issue(All OMAP2420 and OMAP2430ES1.0): > DMA will wrongly buffer elements if packing and bursting is enabled. > This might result in data gets stalled in FIFO at the end of the block. > Workaround: DMA channels must have BUFFERING_DISABLED bit set to guarantee > no data will stay in the DMA FIFO in case inter frame buffering occurs. > Ok, no problem. I'll add this to the next version. This is good to get documented. -- Jarkko -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
