Hi, 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. -- balbi
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