Messages in this thread | | | Date | Thu, 28 Jul 2011 23:24:12 +0530 | Subject | Re: [PATCHv2] DMAEngine: Let dmac drivers to set chan_id | From | Jaswinder Singh <> |
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On 28 July 2011 02:07, Russell King <rmk@arm.linux.org.uk> wrote: > >> On a serious note, my proposal, and the reply, shows the possibility >> of having :- >> a) Client drivers that are truly platform agnostic -- no platform_data >> poking for >> channel selection > > I really doubt that's even possible. Take this setup:
I don't want to suggest anything wrong just because I didn't understand your h/w. I hope you will be kind enough to help me better understand your setup, so that I have a fair chance to present my proposal.
A simple 'yes' or a 'no'(with clarification) is all I ask.
> > MMCI ---> DMAC > > where the DMAC has 32 request signals, and 8 channels. The DMAC is similar to PL330. Only max 8 request-signals can be active at any time. Is my understanding right ?
> The MMCI is connected to two of them. I don't know anything about MMCI. So I assume it is just another third party MMC controller. It simply needs 2 dma channels(for RX, TX each) - be it from a DMAC that has a programmable RequestSignal->Peripheral map or a fixed map. Is my understanding right ?
> The DMAC can supply any of its physical channels for MMCI. The RequestSignal->Peripheral map is decided during board design and can not be changed later. Is my understanding right ?
> Board 1 has the MMCI connected to request signals #1 and #3. > Board 2 has the MMCI connected to request signals #8 and #22. Say, Board1 MMCI_RX -> #1 MMCI_TX -> #3
Board2 MMCI_RX -> #8 MMCI_TX -> #22
> Board 3 has the MMCI connected through an external FPGA mux, which can route the > MMCI requests to DMA request signals #1, #2 or #3. Say Board3 MMCI_RX -> #{1,2,3} MMCI_TX -> #{1,2,3} And you can't change the route(mapping) after the dmac driver has been loaded. Is my understanding right ? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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