It's a bit too much info, but please review the "Overview" section here: http://tiexpressdsp.com/index.php?title=Dma_overview
It attempts to describe challenges in hard-coding DMA resources on systems with multiple cores that must cooperate. Fortunately the DMA resource managers are typically flexible - so long as the users of the resources behave (e.g. codecs ask for resources from FC resource managers rather than hard-code channels). I agree with Kevin, no one should be hard-coding resources, Linux-side/BIOS-side or otherwise, unless perhaps it's a completely closed system. Finally, a detail, DSP Link doesn't manage DSP-side DMA resources - Framework Components and the EDMA3LLD (LLD == Low-Level Driver) do. Chris > -----Original Message----- > From: davinci-linux-open-source-boun...@linux.davincidsp.com > [mailto:davinci-linux-open-source-boun...@linux.davincidsp.com > ] On Behalf Of Kevin Hilman > Sent: Friday, April 17, 2009 5:02 AM > To: Troy Kisky > Cc: davinci-linux-open-source@linux.davincidsp.com > Subject: Re: [PATCH] ARM: DaVinci: edma: reserve dsp dma usage > > Troy Kisky <troy.ki...@boundarydevices.com> writes: > > > Reserve channels 0,1,12,13 and > > slots 78-109 for dsp use on dm644x. > > > > Signed-off-by: Troy Kisky <troy.ki...@boundarydevices.com> > > > > I've only verified that channels 0, and 78-101 need > > reserved, but reserving a little extra seems like > > a good idea. > > I'm not crazy about this hard-coded reservation. > > The DSP code has a kernel-side driver (dsplinkk.) That driver > should be doing the channel reservations. > > Kevin > > > arch/arm/mach-davinci/dm644x.c | 6 ++++++ > > arch/arm/mach-davinci/dma.c | 8 ++++++++ > > arch/arm/mach-davinci/include/mach/edma.h | 7 ++++++- > > 3 files changed, 20 insertions(+), 1 deletions(-) > > > > diff --git a/arch/arm/mach-davinci/dm644x.c > b/arch/arm/mach-davinci/dm644x.c > > index 6a08568..86eb9ef 100644 > > --- a/arch/arm/mach-davinci/dm644x.c > > +++ b/arch/arm/mach-davinci/dm644x.c > > @@ -403,6 +403,12 @@ static struct edma_soc_info > dm644x_edma_info = { > > .n_slot = 128, > > .n_tc = 2, > > .noevent = dma_chan_dm644x_no_event, > > +/* reserve slots 78-109 for dsp use */ > > + .dsp_reserve_slot_min = 78, > > + .dsp_reserve_slot_max = 78 + 31, > > +/* reserve channels 0, 1, 12, 13 for dsp use */ > > + .dsp_reserve_channel_min = 0, > > + .dsp_reserve_channel_max = 13, > > }; > > > > static struct resource edma_resources[] = { > > diff --git a/arch/arm/mach-davinci/dma.c > b/arch/arm/mach-davinci/dma.c > > index 1f58631..f2e6b8a 100644 > > --- a/arch/arm/mach-davinci/dma.c > > +++ b/arch/arm/mach-davinci/dma.c > > @@ -1051,6 +1051,14 @@ static int __init edma_probe(struct > platform_device *pdev) > > while (*noevent != -1) > > set_bit(*noevent++, edma_noevent); > > } > > + for (i = info->dsp_reserve_slot_min; > > + i <= info->dsp_reserve_slot_max; i++) > > + set_bit(i, edma_inuse); > > + > > + for (i = info->dsp_reserve_channel_min; > > + i <= info->dsp_reserve_channel_max; i++) > > + if (test_bit(i, edma_noevent)) > > + set_bit(i, edma_inuse); > > > > irq = platform_get_irq(pdev, 0); > > status = request_irq(irq, dma_irq_handler, 0, "edma", > &pdev->dev); > > diff --git a/arch/arm/mach-davinci/include/mach/edma.h > b/arch/arm/mach-davinci/include/mach/edma.h > > index b467358..cb45960 100644 > > --- a/arch/arm/mach-davinci/include/mach/edma.h > > +++ b/arch/arm/mach-davinci/include/mach/edma.h > > @@ -222,8 +222,13 @@ struct edma_soc_info { > > unsigned n_slot; > > unsigned n_tc; > > > > - /* list of channels with no even trigger; terminated by "-1" */ > > + /* list of channels with no event trigger; terminated by "-1" */ > > const s8 *noevent; > > + u16 dsp_reserve_slot_min; > > + u16 dsp_reserve_slot_max; > > + /* only "no event" channels in range below are reserved */ > > + u16 dsp_reserve_channel_min; > > + u16 dsp_reserve_channel_max; > > }; > > > > #endif > > -- > > 1.5.4.3 > > > > > > _______________________________________________ > > Davinci-linux-open-source mailing list > > Davinci-linux-open-source@linux.davincidsp.com > > > http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source > > _______________________________________________ > Davinci-linux-open-source mailing list > Davinci-linux-open-source@linux.davincidsp.com > http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source > _______________________________________________ Davinci-linux-open-source mailing list Davinci-linux-open-source@linux.davincidsp.com http://linux.davincidsp.com/mailman/listinfo/davinci-linux-open-source
