Re: [Query]: What should we do in txd->tx_submit() and device_issue_pending()
From: viresh kumar
Date: Tue Jul 19 2011 - 05:09:10 EST
On 07/19/2011 02:19 PM, Koul, Vinod wrote:
> (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 https://lkml.org/lkml/2011/5/24/530
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