Messages in this thread | | | Date | Tue, 26 Jul 2011 08:29:29 -0700 | Subject | Re: [PATCHv2] DMAEngine: Let dmac drivers to set chan_id | From | "Williams, Dan J" <> |
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On Tue, Jul 26, 2011 at 7:30 AM, Jaswinder Singh <jaswinder.singh@linaro.org> wrote: > On 26 July 2011 01:38, Williams, Dan J <dan.j.williams@intel.com> wrote: >> Correct, it is meant that chan_id is only a sysfs property. Any >> driver usage that is assuming chan_id is anything more than a >> guaranteed unique number within a given dma_device's list of channels >> is probably inferring too much. > > So you mean dmac/client drivers are wrong if they make use of chan_id. > They shouldn't count upon it's value - which is set by DMA API for a completely > independent purpose, i.e, creating contiguous sysfs entries.
They can count on it being unique, and maybe the fact that it is in the same order as dma_device.channels.
> > Since "chan_id is only a sysfs property" and the fact that it is used > only _once_ > by the DMA API > > In drivers/dma/dmaengine.c > > chan->chan_id = chancnt++; > dev_set_name(&chan->dev->device, "dma%dchan%d", > device->dev_id, chan->chan_id); > > > Can't we do away with chan_id altogether ? by having > > dev_set_name(&chan->dev->device, "dma%dchan%d", > device->dev_id, chancnt++); > > I mean why make every instance of dma_chan bigger by 4bytes ? > > So why shouldn't we remove chan_id completely from the DMA API ?
Good point... Let's remove chan_id from the core and push it into the drivers that need it.
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