From: Marcello Sylvester Bauer sylv@sylv.io
commit a7f3813e589fd8e2834720829a47b5eb914a9afe upstream.
The dummy_hcd transfer scheduler assumes that the internal kernel timer frequency is set to 1000Hz to give a polling interval of 1ms. Reducing the timer frequency will result in an anti-proportional reduction in transfer performance. Switch to a hrtimer to decouple this association.
Signed-off-by: Marcello Sylvester Bauer marcello.bauer@9elements.com Signed-off-by: Marcello Sylvester Bauer sylv@sylv.io Reviewed-by: Alan Stern stern@rowland.harvard.edu Link: https://lore.kernel.org/r/57a1c2180ff74661600e010c234d1dbaba1d0d46.171284396... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Guilherme G. Piccoli gpiccoli@igalia.com --- drivers/usb/gadget/udc/dummy_hcd.c | 35 +++++++++++++++++------------- 1 file changed, 20 insertions(+), 15 deletions(-)
diff --git a/drivers/usb/gadget/udc/dummy_hcd.c b/drivers/usb/gadget/udc/dummy_hcd.c index 0953e1b5c030..dab559d8ee8c 100644 --- a/drivers/usb/gadget/udc/dummy_hcd.c +++ b/drivers/usb/gadget/udc/dummy_hcd.c @@ -30,7 +30,7 @@ #include <linux/slab.h> #include <linux/errno.h> #include <linux/init.h> -#include <linux/timer.h> +#include <linux/hrtimer.h> #include <linux/list.h> #include <linux/interrupt.h> #include <linux/platform_device.h> @@ -240,7 +240,7 @@ enum dummy_rh_state { struct dummy_hcd { struct dummy *dum; enum dummy_rh_state rh_state; - struct timer_list timer; + struct hrtimer timer; u32 port_status; u32 old_status; unsigned long re_timeout; @@ -1301,8 +1301,8 @@ static int dummy_urb_enqueue( urb->error_count = 1; /* mark as a new urb */
/* kick the scheduler, it'll do the rest */ - if (!timer_pending(&dum_hcd->timer)) - mod_timer(&dum_hcd->timer, jiffies + 1); + if (!hrtimer_active(&dum_hcd->timer)) + hrtimer_start(&dum_hcd->timer, ms_to_ktime(1), HRTIMER_MODE_REL);
done: spin_unlock_irqrestore(&dum_hcd->dum->lock, flags); @@ -1323,7 +1323,7 @@ static int dummy_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status) rc = usb_hcd_check_unlink_urb(hcd, urb, status); if (!rc && dum_hcd->rh_state != DUMMY_RH_RUNNING && !list_empty(&dum_hcd->urbp_list)) - mod_timer(&dum_hcd->timer, jiffies); + hrtimer_start(&dum_hcd->timer, ns_to_ktime(0), HRTIMER_MODE_REL);
spin_unlock_irqrestore(&dum_hcd->dum->lock, flags); return rc; @@ -1777,7 +1777,7 @@ static int handle_control_request(struct dummy_hcd *dum_hcd, struct urb *urb, * drivers except that the callbacks are invoked from soft interrupt * context. */ -static void dummy_timer(struct timer_list *t) +static enum hrtimer_restart dummy_timer(struct hrtimer *t) { struct dummy_hcd *dum_hcd = from_timer(dum_hcd, t, timer); struct dummy *dum = dum_hcd->dum; @@ -1808,8 +1808,6 @@ static void dummy_timer(struct timer_list *t) break; }
- /* FIXME if HZ != 1000 this will probably misbehave ... */ - /* look at each urb queued by the host side driver */ spin_lock_irqsave(&dum->lock, flags);
@@ -1817,7 +1815,7 @@ static void dummy_timer(struct timer_list *t) dev_err(dummy_dev(dum_hcd), "timer fired with no URBs pending?\n"); spin_unlock_irqrestore(&dum->lock, flags); - return; + return HRTIMER_NORESTART; } dum_hcd->next_frame_urbp = NULL;
@@ -1995,10 +1993,12 @@ static void dummy_timer(struct timer_list *t) dum_hcd->udev = NULL; } else if (dum_hcd->rh_state == DUMMY_RH_RUNNING) { /* want a 1 msec delay here */ - mod_timer(&dum_hcd->timer, jiffies + msecs_to_jiffies(1)); + hrtimer_start(&dum_hcd->timer, ms_to_ktime(1), HRTIMER_MODE_REL); }
spin_unlock_irqrestore(&dum->lock, flags); + + return HRTIMER_NORESTART; }
/*-------------------------------------------------------------------------*/ @@ -2387,7 +2387,7 @@ static int dummy_bus_resume(struct usb_hcd *hcd) dum_hcd->rh_state = DUMMY_RH_RUNNING; set_link_state(dum_hcd); if (!list_empty(&dum_hcd->urbp_list)) - mod_timer(&dum_hcd->timer, jiffies); + hrtimer_start(&dum_hcd->timer, ns_to_ktime(0), HRTIMER_MODE_REL); hcd->state = HC_STATE_RUNNING; } spin_unlock_irq(&dum_hcd->dum->lock); @@ -2465,7 +2465,8 @@ static DEVICE_ATTR_RO(urbs);
static int dummy_start_ss(struct dummy_hcd *dum_hcd) { - timer_setup(&dum_hcd->timer, dummy_timer, 0); + hrtimer_init(&dum_hcd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + dum_hcd->timer.function = dummy_timer; dum_hcd->rh_state = DUMMY_RH_RUNNING; dum_hcd->stream_en_ep = 0; INIT_LIST_HEAD(&dum_hcd->urbp_list); @@ -2494,7 +2495,8 @@ static int dummy_start(struct usb_hcd *hcd) return dummy_start_ss(dum_hcd);
spin_lock_init(&dum_hcd->dum->lock); - timer_setup(&dum_hcd->timer, dummy_timer, 0); + hrtimer_init(&dum_hcd->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + dum_hcd->timer.function = dummy_timer; dum_hcd->rh_state = DUMMY_RH_RUNNING;
INIT_LIST_HEAD(&dum_hcd->urbp_list); @@ -2513,8 +2515,11 @@ static int dummy_start(struct usb_hcd *hcd)
static void dummy_stop(struct usb_hcd *hcd) { - device_remove_file(dummy_dev(hcd_to_dummy_hcd(hcd)), &dev_attr_urbs); - dev_info(dummy_dev(hcd_to_dummy_hcd(hcd)), "stopped\n"); + struct dummy_hcd *dum_hcd = hcd_to_dummy_hcd(hcd); + + hrtimer_cancel(&dum_hcd->timer); + device_remove_file(dummy_dev(dum_hcd), &dev_attr_urbs); + dev_info(dummy_dev(dum_hcd), "stopped\n"); }
/*-------------------------------------------------------------------------*/