On Friday 11 April 2014 03:12 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, the current series has an EDMA specific way of managing priority. > >> 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. If not then we can add this in dma_slave_config ? The priority will be per-channel not per-transaction (at least for the use case we are talking about here). Thanks, Sekhar -- 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
