Hello uvc gadget developers, I'm working on a 5.15.41 based kernel on a qcom chipset with the dwc3 controller and I'm encountering two problems related to the recent performance improvement changes: https://patchwork.kernel.org/project/linux-usb/patch/20210628155311.16762-5-m.grzeschik@xxxxxxxxxxxxxx/ and https://patchwork.kernel.org/project/linux-usb/patch/20210628155311.16762-6-m.grzeschik@xxxxxxxxxxxxxx/ If I revert these two changes, then I have much improved stability and a transmission problem I'm seeing is gone. Has there been any success from others on 5.15 with this uvc improvement and any recommendations for my current problems? Those being: 1) a smmu panic, snippet here: <3>[ 718.314900][ T803] arm-smmu 15000000.apps-smmu: Unhandled arm-smmu context fault from a600000.dwc3! <3>[ 718.314994][ T803] arm-smmu 15000000.apps-smmu: FAR = 0x00000000efe60800 <3>[ 718.315023][ T803] arm-smmu 15000000.apps-smmu: PAR = 0x0000000000000000 <3>[ 718.315048][ T803] arm-smmu 15000000.apps-smmu: FSR = 0x40000402 [TF R SS ] <3>[ 718.315074][ T803] arm-smmu 15000000.apps-smmu: FSYNR0 = 0x5f0003 <3>[ 718.315096][ T803] arm-smmu 15000000.apps-smmu: FSYNR1 = 0xaa02 <3>[ 718.315117][ T803] arm-smmu 15000000.apps-smmu: context bank# = 0x1b <3>[ 718.315141][ T803] arm-smmu 15000000.apps-smmu: TTBR0 = 0x001b0000c2a92000 <3>[ 718.315165][ T803] arm-smmu 15000000.apps-smmu: TTBR1 = 0x001b000000000000 <3>[ 718.315192][ T803] arm-smmu 15000000.apps-smmu: SCTLR = 0x0a5f00e7 ACTLR = 0x00000003 <3>[ 718.315245][ T803] arm-smmu 15000000.apps-smmu: CBAR = 0x0001f300 <3>[ 718.315274][ T803] arm-smmu 15000000.apps-smmu: MAIR0 = 0xf404ff44 MAIR1 = 0x0000efe4 <3>[ 718.315297][ T803] arm-smmu 15000000.apps-smmu: SID = 0x40 <3>[ 718.315318][ T803] arm-smmu 15000000.apps-smmu: Client info: BID=0x5, PID=0xa, MID=0x2 <3>[ 718.315377][ T803] arm-smmu 15000000.apps-smmu: soft iova-to-phys=0x0000000000000000 I can reduce this panic with the proposed patch, but it still happens until I disable the "req->no_interrupt = 1" logic. 2) The frame is not fully transmitted in dwc3 with sg support enabled. There seems to be a mapping limit I'm seeing where only the roughly first 70% of the total frame is sent. Interestingly, if I allocate a larger size for the buffer upfront, in uvc_queue_setup(), like sizes[0] = video->imagesize * 3. Then the issue rarely happens. For example, when I do YUYV I see green, uninitialized data, at the bottom part of the frame. If I do MJPG with smaller filled sizes, the transmission is fine. +-------------------------+ | | | | | | | Good data | | | | | | | +-------------------------+ |xxxxxxxxxxxxxxxxxxxxxxxxx| |xxxx Bad data xxxxxxxxx| |xxxxxxxxxxxxxxxxxxxxxxxxx| +-------------------------+ Appreciate any thoughts or feedback related to these issues. Dan Vacura (1): usb: gadget: uvc: fix sg handling in error case drivers/usb/gadget/function/uvc_queue.c | 8 +++++--- drivers/usb/gadget/function/uvc_queue.h | 2 +- drivers/usb/gadget/function/uvc_video.c | 18 ++++++++++++++---- 3 files changed, 20 insertions(+), 8 deletions(-) -- 2.20.4
