[ +CC: linux-usb ] On Mon, Jan 16, 2017 at 12:14:03PM +0100, Boris Brezillon wrote: > On Mon, 16 Jan 2017 11:54:23 +0100 > Antoine Aubert <a.aubert@xxxxxxxxxxx> wrote: > > > Also, I made a big misunderstanding > > > > With EHCI + OHCI = high level of softirq (USB2.0) > > Well, the number of irqs and softirqs are likely to be related (you > usually trigger a softirq after you received an hardirq). > > > > > OHCI only = normal level > > What about EHCI only? And what happens if you only plug 1 device? > Please share the content of /proc/interrupts (and everything you think > is relevant) for each of these cases. > > > > > Le 16/01/2017 à 11:31, Antoine Aubert a écrit : > > > Thx for your answer Boris > > > > > > Le 16/01/2017 à 10:02, Boris Brezillon a écrit : > > >> Hi Antoine, > > >> > > >> On Mon, 16 Jan 2017 08:45:58 +0100 > > >> Antoine Aubert <a.aubert@xxxxxxxxxxx> wrote: > > >> > > >>> Hi, > > >>> > > >>> Im working on a AT91SAM9G25cu board > > >>> (arch/arm/boot/dts/at91-kizboxmini.dts). We use linux-4.1.31, and when > > >>> OHCI is enabled, I got some wired effects. > > >> Can you test on a more recent kernel (4.9 or 4.10-rc4)? > > > I'll give a try, just need little time ;) > > >>> eg with 3 FTDI pluged, interrupts: more than 3.5k/s, cpu softirq > 24%, > > >>> loadavg > 0.5 > > >> Can you check which interrupt is triggered (cat /proc/interrupts), > > > cat /proc/interrupts > > > CPU0 > > > 16: 2286 atmel-aic 1 Level pmc, at91_tick, at91_rtc, ttyS0 > > > 17: 0 PMC 17 Level main_rc_osc > > > 18: 0 PMC 0 Level main_osc > > > 19: 0 PMC 16 Level mainck > > > 20: 0 PMC 1 Level clk-plla > > > 21: 0 PMC 6 Level clk-utmi > > > 22: 0 PMC 3 Level clk-master > > > 23: 945527 atmel-aic 17 Level tc_clkevt > > > 24: 21815 atmel-aic 20 Level at_hdmac > > > 25: 0 atmel-aic 21 Level at_hdmac > > > 30: 120299 atmel-aic 24 Level eth0 > > > 31: 22783651 atmel-aic 22 Level ehci_hcd:usb1, ohci_hcd:usb2 > > > 99: 0 GPIO 16 Edge PB_RST > > > 100: 0 GPIO 17 Edge PB_PROG > > > Err: 0 Note that the ftdi driver uses a low-latency setting by default which implies that the device sends a status update every millisecond. Hence, the 1k interrupts per second (per device) while the port is open is expected. You can disable the low-latency behaviour using setserial: setserial /dev/ttyUSB0 ^low_latency and see the number of interrupts drop to 1/16th. This can then be reduced further by changing the latency_timer from its (non-low-latency) default of 16 ms, for example: echo 64 >/sys/bus/usb-serial/devices/ttyUSB0/latency_timer Johan -- 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
