| Message ID | 6295dbb84ca76884551df9eb157cce569377a22c.1712843963.git.sylv@sylv.io |
|---|---|
| State | New |
| Headers | show |
| Series | usb: gadget: dummy_hcd: Switch to hrtimers for better performance | expand |
On Thu, Apr 11, 2024 at 05:22:11PM +0200, Marcello Sylvester Bauer wrote: > Currently, the transfer polling interval is set to 1ms, which is the > frame rate of full-speed and low-speed USB. The USB 2.0 specification > introduces microframes (125 microseconds) to improve the timing > precision of data transfers. > > Reducing the transfer interval to 1 microframe increases data throughput > for high-speed and super-speed USB communication > > Signed-off-by: Marcello Sylvester Bauer <marcello.bauer@9elements.com> > Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.io> > --- > drivers/usb/gadget/udc/dummy_hcd.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/gadget/udc/dummy_hcd.c b/drivers/usb/gadget/udc/dummy_hcd.c > index dab559d8ee8c..f37b0d8386c1 100644 > --- a/drivers/usb/gadget/udc/dummy_hcd.c > +++ b/drivers/usb/gadget/udc/dummy_hcd.c > @@ -50,6 +50,8 @@ > #define POWER_BUDGET 500 /* in mA; use 8 for low-power port testing */ > #define POWER_BUDGET_3 900 /* in mA */ > > +#define DUMMY_TIMER_INT_NSECS 125000 /* 1 microframe */ If the is_super_speed and is_high_speed module parameters are both false then the timer should run at 1-ms intervals. So this needs to be something that can be adjusted at runtime, not a constant. Alan Stern
diff --git a/drivers/usb/gadget/udc/dummy_hcd.c b/drivers/usb/gadget/udc/dummy_hcd.c index dab559d8ee8c..f37b0d8386c1 100644 --- a/drivers/usb/gadget/udc/dummy_hcd.c +++ b/drivers/usb/gadget/udc/dummy_hcd.c @@ -50,6 +50,8 @@ #define POWER_BUDGET 500 /* in mA; use 8 for low-power port testing */ #define POWER_BUDGET_3 900 /* in mA */ +#define DUMMY_TIMER_INT_NSECS 125000 /* 1 microframe */ + static const char driver_name[] = "dummy_hcd"; static const char driver_desc[] = "USB Host+Gadget Emulator"; @@ -1302,7 +1304,7 @@ static int dummy_urb_enqueue( /* kick the scheduler, it'll do the rest */ if (!hrtimer_active(&dum_hcd->timer)) - hrtimer_start(&dum_hcd->timer, ms_to_ktime(1), HRTIMER_MODE_REL); + hrtimer_start(&dum_hcd->timer, ns_to_ktime(DUMMY_TIMER_INT_NSECS), HRTIMER_MODE_REL); done: spin_unlock_irqrestore(&dum_hcd->dum->lock, flags); @@ -1993,7 +1995,7 @@ static enum hrtimer_restart dummy_timer(struct hrtimer *t) dum_hcd->udev = NULL; } else if (dum_hcd->rh_state == DUMMY_RH_RUNNING) { /* want a 1 msec delay here */ - hrtimer_start(&dum_hcd->timer, ms_to_ktime(1), HRTIMER_MODE_REL); + hrtimer_start(&dum_hcd->timer, ns_to_ktime(DUMMY_TIMER_INT_NSECS), HRTIMER_MODE_REL); } spin_unlock_irqrestore(&dum->lock, flags);