The dwc2 interrupt handler is quite slow. On rk3288 with a few things plugged into the ports and with cpufreq locked at 696MHz (to simulate real world idle system), I can easily observe dwc2_handle_hcd_intr() taking > 120 us, sometimes > 150 us. Note that SOF interrupts come every 125 us with high speed USB, so taking > 120 us in the interrupt handler is a big deal. The patches here will speed up the interrupt controller significantly. After this series, I have a hard time seeing the interrupt controller taking > 20 us and I don't ever see it taking > 30 us ever in my tests unless I bring the cpufreq back down. With the cpufreq at 126 MHz I can still see the interrupt handler take > 50 us, so I'm sure we could improve this further. ...but hey, it's a start. This series also shows big speed improvements when testing with a USB Gigabit Ethernet adapter. Previously the tested adapter would top out at about 15MB/s. After these changes it gets about 23MB/s. In addition to the speedup, this series also has the advantage of simplifying dwc2 and making it more like everyone else (introducing the possibility of future simplifications). Picking this series up will help your diffstat and likely win you friends. ;) === Steps for gathering data with ftrace: cd /sys/devices/system/cpu/cpu0/cpufreq/ echo userspace > scaling_governor echo 696000 > scaling_setspeed cd /sys/kernel/debug/tracing echo 0 > tracing_on echo "" > trace echo nop > current_tracer echo function_graph > current_tracer echo dwc2_handle_hcd_intr > set_graph_function echo dwc2_handle_common_intr >> set_graph_function echo dwc2_handle_hcd_intr > set_ftrace_filter echo dwc2_handle_common_intr >> set_ftrace_filter echo funcgraph-abstime > trace_options echo 70 > tracing_thresh echo 1 > /sys/kernel/debug/tracing/tracing_on sleep 2 cat trace === NOTE: This series doesn't replace any other patches I've submitted recently, it merely adds another set of changes that upstream could benefit from. Changes in v2: - Add a warn if setup_dma is not aligned (Julius Werner). - Periodic bandwidth release delay new for V2 - Commit message now says that URB giveback change needs delay change. Douglas Anderson (4): usb: dwc2: rockchip: Make the max_transfer_size automatic usb: dwc2: host: Get aligned DMA in a more supported way usb: dwc2: host: Add a delay before releasing periodic bandwidth usb: dwc2: host: Giveback URB in tasklet context drivers/usb/dwc2/core.c | 21 +--- drivers/usb/dwc2/hcd.c | 174 +++++++++++++++---------------- drivers/usb/dwc2/hcd.h | 16 ++- drivers/usb/dwc2/hcd_intr.c | 65 ------------ drivers/usb/dwc2/hcd_queue.c | 239 ++++++++++++++++++++++++++++++++----------- drivers/usb/dwc2/platform.c | 2 +- 6 files changed, 273 insertions(+), 244 deletions(-) -- 2.6.0.rc2.230.g3dd15c0 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
