Commit cfd07ec8 authored by P33M's avatar P33M Committed by popcornmix
Browse files

dwc_otg: implement tasklet for returning URBs to usbcore hcd layer 

The dwc_otg driver interrupt handler for transfer completion will spend
a very long time with interrupts disabled when a URB is completed -
this is because usb_hcd_giveback_urb is called from within the handler
which for a USB device driver with complicated processing (e.g. webcam)
will take an exorbitant amount of time to complete. This results in
missed completion interrupts for other USB packets which lead to them
being dropped due to microframe overruns.

This patch splits returning the URB to the usb hcd layer into a
high-priority tasklet. This will have most benefit for isochronous IN
transfers but will also have incidental benefit where multiple periodic
devices are active at once.
parent 21e61ec4

drivers/usb/host/dwc_common_port/dwc_common_linux.c

+5 −0
Original line number Diff line number Diff line
@@ -991,6 +991,11 @@ void DWC_TASK_SCHEDULE(dwc_tasklet_t *task) 
	tasklet_schedule(&task->t);

}



void DWC_TASK_HI_SCHEDULE(dwc_tasklet_t *task)

{

	tasklet_hi_schedule(&task->t);

}





/* workqueues

 - run in process context (can sleep)

drivers/usb/host/dwc_common_port/dwc_list.h

+7 −7
Original line number Diff line number Diff line
@@ -384,17 +384,17 @@ struct { \ 
#define DWC_TAILQ_PREV(elm, headname, field)				\

	(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))

#define DWC_TAILQ_EMPTY(head)						\

	(TAILQ_FIRST(head) == TAILQ_END(head))

	(DWC_TAILQ_FIRST(head) == DWC_TAILQ_END(head))



#define DWC_TAILQ_FOREACH(var, head, field)				\

	for((var) = TAILQ_FIRST(head);					\

	    (var) != TAILQ_END(head);					\

	    (var) = TAILQ_NEXT(var, field))

	for ((var) = DWC_TAILQ_FIRST(head);				\

	    (var) != DWC_TAILQ_END(head);				\

	    (var) = DWC_TAILQ_NEXT(var, field))



#define DWC_TAILQ_FOREACH_REVERSE(var, head, headname, field)		\

	for((var) = TAILQ_LAST(head, headname);				\

	    (var) != TAILQ_END(head);					\

	    (var) = TAILQ_PREV(var, headname, field))

	for ((var) = DWC_TAILQ_LAST(head, headname);			\

	    (var) != DWC_TAILQ_END(head);				\

	    (var) = DWC_TAILQ_PREV(var, headname, field))



/*

 * Tail queue functions.

drivers/usb/host/dwc_common_port/dwc_os.h

+2 −0
Original line number Diff line number Diff line
@@ -981,6 +981,8 @@ extern void DWC_TASK_FREE(dwc_tasklet_t *task); 
extern void DWC_TASK_SCHEDULE(dwc_tasklet_t *task);

#define dwc_task_schedule DWC_TASK_SCHEDULE



extern void DWC_TASK_HI_SCHEDULE(dwc_tasklet_t *task);

#define dwc_task_hi_schedule DWC_TASK_HI_SCHEDULE



/** @name Timer

 *

drivers/usb/host/dwc_otg/dwc_otg_hcd.c

+33 −1
Original line number Diff line number Diff line
@@ -40,6 +40,9 @@ 
 * header file.

 */



#include <linux/usb.h>

#include <linux/usb/hcd.h>



#include "dwc_otg_hcd.h"

#include "dwc_otg_regs.h"
@@ -694,6 +697,31 @@ static void reset_tasklet_func(void *data) 
	dwc_otg_hcd->flags.b.port_reset_change = 1;

}



static void completion_tasklet_func(void *ptr)

{

	dwc_otg_hcd_t *hcd = (dwc_otg_hcd_t *) ptr;

	struct urb *urb;

	urb_tq_entry_t *item;

	dwc_irqflags_t flags;



	DWC_SPINLOCK_IRQSAVE(hcd->lock, &flags);

	while (!DWC_TAILQ_EMPTY(&hcd->completed_urb_list)) {

		item = DWC_TAILQ_FIRST(&hcd->completed_urb_list);

		urb = item->urb;

		DWC_TAILQ_REMOVE(&hcd->completed_urb_list, item,

				urb_tq_entries);

		DWC_SPINUNLOCK_IRQRESTORE(hcd->lock, flags);

		DWC_FREE(item);



		usb_hcd_unlink_urb_from_ep(hcd->priv, urb);

		usb_hcd_giveback_urb(hcd->priv, urb, urb->status);



		DWC_SPINLOCK_IRQSAVE(hcd->lock, &flags);

	}

	DWC_SPINUNLOCK_IRQRESTORE(hcd->lock, flags);

	return;

}



static void qh_list_free(dwc_otg_hcd_t * hcd, dwc_list_link_t * qh_list)

{

	dwc_list_link_t *item;
@@ -833,6 +861,7 @@ static void dwc_otg_hcd_free(dwc_otg_hcd_t * dwc_otg_hcd) 


	DWC_TIMER_FREE(dwc_otg_hcd->conn_timer);

	DWC_TASK_FREE(dwc_otg_hcd->reset_tasklet);

	DWC_TASK_FREE(dwc_otg_hcd->completion_tasklet);



#ifdef DWC_DEV_SRPCAP

	if (dwc_otg_hcd->core_if->power_down == 2 &&
@@ -877,7 +906,7 @@ int dwc_otg_hcd_init(dwc_otg_hcd_t * hcd, dwc_otg_core_if_t * core_if) 
	DWC_LIST_INIT(&hcd->periodic_sched_ready);

	DWC_LIST_INIT(&hcd->periodic_sched_assigned);

	DWC_LIST_INIT(&hcd->periodic_sched_queued);



	DWC_TAILQ_INIT(&hcd->completed_urb_list);

	/*

	 * Create a host channel descriptor for each host channel implemented

	 * in the controller. Initialize the channel descriptor array.
@@ -915,6 +944,9 @@ int dwc_otg_hcd_init(dwc_otg_hcd_t * hcd, dwc_otg_core_if_t * core_if) 


	/* Initialize reset tasklet. */

	hcd->reset_tasklet = DWC_TASK_ALLOC("reset_tasklet", reset_tasklet_func, hcd);



	hcd->completion_tasklet = DWC_TASK_ALLOC("completion_tasklet",

						completion_tasklet_func, hcd);

#ifdef DWC_DEV_SRPCAP

	if (hcd->core_if->power_down == 2) {

		/* Initialize Power on timer for Host power up in case hibernation */

drivers/usb/host/dwc_otg/dwc_otg_hcd.h

+10 −0
Original line number Diff line number Diff line
@@ -374,6 +374,13 @@ typedef struct dwc_otg_qh { 


DWC_CIRCLEQ_HEAD(hc_list, dwc_hc);



typedef struct urb_tq_entry {

	struct urb *urb;

	DWC_TAILQ_ENTRY(urb_tq_entry) urb_tq_entries;

} urb_tq_entry_t;



DWC_TAILQ_HEAD(urb_list, urb_tq_entry);



/**

 * This structure holds the state of the HCD, including the non-periodic and

 * periodic schedules.
@@ -551,6 +558,9 @@ struct dwc_otg_hcd { 
	/* Tasket to do a reset */

	dwc_tasklet_t *reset_tasklet;



	dwc_tasklet_t *completion_tasklet;

	struct urb_list completed_urb_list;



	/*  */

	dwc_spinlock_t *lock;

	dwc_spinlock_t *channel_lock;