USB: OHCI: high softirq load

[Boris Brezillon]

Hi Antoine,

On Mon, 16 Jan 2017 08:45:58 +0100
Antoine Aubert <a.aubert at overkiz.com> 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)?

> 
> 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), and
enable debug messages in drivers/usb/host/ohci-at91.c?

Thanks,

Boris

> 
> This issue disappear when disabling OHCI and use EHCI only.
> 
> What are the usual causes, and where to begin with ?
> 
> Thanks in advance,
>