RE: [Query]: What should we do in txd->tx_submit() anddevice_issue_pending()

From: Koul, Vinod
Date: Tue Jul 19 2011 - 04:50:15 EST

(pls wrap your email to 80lines, I have reflowed below for readability)
> Hi Dan/Vinod,
> I have one query regarding implementation of few routines in DMA drivers.
> What the exact purpose of txd->tx_submit() and device_issue_pending() routines?
> Should tx_submit() always start physical transfer (Obviously, if channel is
> free)? Or should it just queue requests and then finally a call to
> device_issue_pending() must start physical transfers?
(reflowed your email for 80lines)
tx_submit is not supposed to start the transfer, it is supposed to add the
descriptors in dma driver's queue. The issue_pending is supposed to actually
start the transfer. The reasons were well articulated is discussion we had
when we did the DMA documentation.
Pls see

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