Hi again, Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> writes: > Bin Liu <b-liu@xxxxxx> writes: >> On Fri, Mar 18, 2016 at 08:59:48AM +0200, Felipe Balbi wrote: >>> >>> Hi, >>> >>> Bin Liu <binmlist@xxxxxxxxx> writes: >>> > [ text/plain ] >>> > Hi, >>> > >>> > On Fri, Mar 11, 2016 at 6:54 AM, Felipe Balbi >>> > <felipe.balbi@xxxxxxxxxxxxxxx> wrote: >>> >> previously we were using a maximum of 32 TRBs per >>> >> endpoint. With each TRB being 16 bytes long, we were >>> >> using 512 bytes of memory for each endpoint. >>> >> >>> >> However, SLAB/SLUB will always allocate PAGE_SIZE >>> >> chunks. In order to better utilize the memory we >>> >> allocate and to allow deeper queues for gadgets >>> >> which would benefit from it (g_ether comes to mind), >>> >> let's increase the maximum to 256 TRBs which rounds >>> >> up to 4096 bytes for each endpoint. >>> > >>> > Do we want to increase the same for event ring buffers as >>> > while, which is allocated by dma_alloc_coherent(), which >>> > is also at PAGE_SIZE chunks, right? >>> >>> I could, but that's much less important. Currently we have up to 2 >> >> I agree it is less important, the only issue I see is wasting of memory. >> The device I am working on right now has two dwc3 controllers, each >> allocates 16 event buffers, so for the total of 128KB allocated pages, >> only 8KB is really used, 120KB is wasted. >> >> Seems dma pool makes more sense in here? > > I don't know. I think the real thing is that I really need to revisit > that part of the code/databook. The whole "multiple interrupters" seems > like it's only really necessary for host side. Which means that we could > drop all the loops for multiple event buffers and always use a single > one. > > Do you wanna test the following ? > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c > index 17fd81447c9f..ebb3ee9c06f1 100644 > --- a/drivers/usb/dwc3/core.c > +++ b/drivers/usb/dwc3/core.c > @@ -237,8 +237,7 @@ static int dwc3_alloc_event_buffers(struct dwc3 *dwc, unsigned length) > int num; > int i; > > - num = DWC3_NUM_INT(dwc->hwparams.hwparams1); > - dwc->num_event_buffers = num; > + dwc->num_event_buffers = 1; > > dwc->ev_buffs = devm_kzalloc(dwc->dev, sizeof(*dwc->ev_buffs) * num, > GFP_KERNEL); > > I'll re-read what these bits actually mean. I have a strong feeling we > could (should?) be ignoring them for the peripheral side. Okay, so when we're configuring the endpoints, we could route endpoint interrupts to different event buffers. I really think that's really unimportant for us, specially since we end up using a single IRQ line. I guess I'll just go ahead and remove that code. If it turns out we decide to use it, we shouldn't really be using a loop in the hardirq handler anyway. -- balbi
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