On Fri, Apr 11, 2014 at 02:32:28PM +0300, Peter Ujfalusi wrote: > Hi Vinod, > > On 04/11/2014 12:42 PM, Vinod Koul wrote: > > On Fri, Apr 11, 2014 at 12:38:00PM +0300, Peter Ujfalusi wrote: > >> On 04/11/2014 11:56 AM, Sekhar Nori wrote: > >>> On Friday 11 April 2014 02:20 PM, Peter Ujfalusi wrote: > >>>> On 04/11/2014 11:17 AM, Sekhar Nori wrote: > >>>>> On Tuesday 01 April 2014 06:36 PM, Peter Ujfalusi wrote: > >>>>>> Use the EVENTQ_1 for default and leave the EVENTQ_0 to be used by high > >>>>>> priority channels, like audio. > >>>>>> > >>>>>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx> > >>>>> > >>>>> Acked-by: Sekhar Nori <nsekhar@xxxxxx> > >>>>> > >>>>>> --- > >>>>>> arch/arm/common/edma.c | 3 ++- > >>>>>> 1 file changed, 2 insertions(+), 1 deletion(-) > >>>>>> > >>>>>> diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c > >>>>>> index 86a8b263278f..19520e2519d9 100644 > >>>>>> --- a/arch/arm/common/edma.c > >>>>>> +++ b/arch/arm/common/edma.c > >>>>>> @@ -1546,7 +1546,8 @@ static int edma_of_parse_dt(struct device *dev, > >>>>>> > >>>>>> pdata->queue_priority_mapping = queue_priority_map; > >>>>>> > >>>>>> - pdata->default_queue = 0; > >>>>>> + /* select queue 1 as default */ > >>>>> > >>>>> It will be nice to expand the comment with explanation of why this is > >>>>> being chosen as default (lower priority queue by default for typical > >>>>> bulk data transfer). > >>>> > >>>> Yes, extended comment is a good idea. > >>>> > >>>> For the next version I think I'm going to change the code around default > >>>> TC/Queue and the non default queue selection, mostly based on Joel's comment: > >>>> > >>>> EVENTQ_1 as default queue. > >>>> Set the EVENTQ_1 priority to 7 > >>>> EVENTQ_0 priority is going to stay 0 and EVENTQ_2 as 2 > >>>> > >>>> Add new member to struct edma, like high_pri_queue. > >>>> When we set the queue priorities in edma_probe() we look for the highest > >>>> priority queue and save the number in high_pri_queue. > >>>> > >>>> I will rename the edma_request_non_default_queue() to > >>>> edma_request_high_pri_queue() and it will assign the channel to the high > >>>> priority queue. > >>>> > >>>> I think this way it is going to be more explicit and IMHO a bit more safer in > >>>> a sense the we are going to get high priority when we ask for it. > >>> > >>> Sounds much better. I had posted some ideas about adding support for > >>> channel priority in the core code but we can leave that for Vinod and > >>> Dan to say if they really see a need for that. > > Is it part of this series? > > No, it is not. The original series tackled the DMA queue selection within the > edma driver stack. It was selecting high priority channel for cyclic (audio) > use only, all other DMA channels were executed on a lower priority queue. > > >> If we do it via the dmaengine core I think it would be better to have a new > >> flag to be passed to dmaengine_prep_dma_*(). > >> We could have for example: > >> DMA_PREP_HIGH_PRI as flag to indicate that we need high priority DMA if it is > >> possible. > >> We can watch for this flag in the edma driver and act accordingly. > >> ALSA's dmaengine_pcm_prepare_and_submit() could set this flag unconditionally > >> since audio should be treated in this way if the DMA IP can do this. > > > > Will the priority be different for each descriptor or would be based on channel > > usage. > > I would say that it is channel based config. I don't see the reason why would > one mix different priorities on a configured channel between descriptors. > > > If not then we can add this in dma_slave_config ? > > So adding to the struct for example: > bool high_priority; In designware controller, we can have channel priorties from 0 to 7 which IIRC 7 being highest. So bool wont work. unsigned int/u8 would be good. How about your controller, is it binary? -- ~Vinod > > I'm not sure if it helps if we have let's say three priority level like, low, > normal and high. > I don't think that any client would ask for low priority instead using the > normal priority. > > > I can forsee its usage on slave controllers, so yes its useful :) > > True I'm sure it is going to be used as soon as it is available if the HW > supports priorities. > > -- > Péter -- -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
