Re: [PATCH 1/3] dmaengine: Allow controller drivers to set channelids

From: Viresh Kumar
Date: Sun Nov 27 2011 - 23:05:54 EST


On 9/28/2011 2:38 PM, Vinod Koul wrote:
> On Thu, 2011-09-22 at 16:13 +0530, Viresh Kumar wrote:
>> > Currently value of chan_id field is updated by dmaengine.c while the dma device
>> > is registered. In some cases the controller driver may need to assign channel
>> > numbers by itself. For example, dw_dmac.c wants to control the order in which
>> > channels are allocated by dmaengine. So it added channels inside channel list of
>> > dma_device in reverse order. Now channel 7 is allocated first and channel 0 is
>> > allocated last.
>> >
>> > But as the channel ids are updated by dmaengine, channel numbers in sysfs will
>> > be overwritten if controller has added channels in reverse order. To represent
>> > correct channel number in sysfs, it is required that dmaengine must not assume
>> > that first channel in list is channel 0 and last is 7.
> to dmaengine, this is just a channel representation in sysfs and nothing
> more. If damc is assuming that this is same as what dmaengine will do
> then dmac is wrong.
>
> Nevertheless, Dan was okay with changing this representation.
> Dan I would need your comments/Ack before we discuss this further

Dan/Vinod,

Any feedback on this patchset?

--
viresh
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