Commit a7f3813e authored by Marcello Sylvester Bauer's avatar Marcello Sylvester Bauer Committed by Greg Kroah-Hartman
Browse files

usb: gadget: dummy_hcd: Switch to hrtimer transfer scheduler 



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: default avatarMarcello Sylvester Bauer <marcello.bauer@9elements.com>
Signed-off-by: default avatarMarcello Sylvester Bauer <sylv@sylv.io>
Reviewed-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/57a1c2180ff74661600e010c234d1dbaba1d0d46.1712843963.git.sylv@sylv.io


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 920e7522

drivers/usb/gadget/udc/dummy_hcd.c

+20 −15
Original line number Diff line number Diff line
@@ -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");

}



/*-------------------------------------------------------------------------*/