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Commit fe9c8ba2 authored by Jack Pham's avatar Jack Pham Committed by Hemant Kumar
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usb: dwc3: gadget: Keep track of IRQ timing statistics 



It may be useful to debug how much time is spent in the
DWC3 hard IRQ context. Add low-overhead statistics counters
which keep a histogram of the last 10 interrupts' time of
occurrence, time spent, and number of events read (which will
get processed in the bottom half handler).

Change-Id: I466144d8141f4236b9fb834dded93225b56d0422
Signed-off-by: default avatarJack Pham <jackp@codeaurora.org>
Signed-off-by: default avatarHemant Kumar <hemantk@codeaurora.org>
parent a4c7b78a

drivers/usb/dwc3/core.h

+15 −0
Original line number Diff line number Diff line
@@ -906,6 +906,8 @@ struct dwc3_scratchpad_array { 
	__le64	dma_adr[DWC3_MAX_HIBER_SCRATCHBUFS];

};



#define MAX_INTR_STATS					10



/**

 * struct dwc3 - representation of our controller

 * @drd_work: workqueue used for role swapping
@@ -1028,6 +1030,10 @@ struct dwc3_scratchpad_array { 
 * @core_id: usb core id to differentiate different controller

 * @index: dwc3's instance number

 * @dwc_ipc_log_ctxt: dwc3 ipc log context

 * @irq_cnt: total irq count

 * @bh_completion_time: time taken for taklet completion

 * @bh_handled_evt_cnt: no. of events handled by tasklet per interrupt

 * @bh_dbg_index: index for capturing bh_completion_time and bh_handled_evt_cnt

 */

struct dwc3 {

	struct work_struct	drd_work;
@@ -1203,6 +1209,15 @@ struct dwc3 { 
	unsigned int		index;

	void			*dwc_ipc_log_ctxt;

	struct dwc3_gadget_events	dbg_gadget_events;



	/* IRQ timing statistics */

	unsigned long		irq_cnt;

	unsigned int		bh_completion_time[MAX_INTR_STATS];

	unsigned int		bh_handled_evt_cnt[MAX_INTR_STATS];

	ktime_t			irq_start_time[MAX_INTR_STATS];

	unsigned int		irq_completion_time[MAX_INTR_STATS];

	unsigned int		irq_event_count[MAX_INTR_STATS];

	unsigned int		irq_dbg_index;

};



#define work_to_dwc(w)		(container_of((w), struct dwc3, drd_work))

drivers/usb/dwc3/debugfs.c

+18 −0
Original line number Diff line number Diff line
@@ -869,6 +869,24 @@ static int dwc3_gadget_int_events_show(struct seq_file *s, void *unused) 
		dbg_gadget_events->cmdcmplt);

	seq_printf(s, "unknown_event:%u\n", dbg_gadget_events->unknown_event);



	seq_printf(s, "\n\t== Last %d interrupts stats ==\t\n", MAX_INTR_STATS);

	seq_puts(s, "@ time (us):\t");

	for (i = 0; i < MAX_INTR_STATS; i++)

		seq_printf(s, "%lld\t", ktime_to_us(dwc->irq_start_time[i]));

	seq_puts(s, "\nhard irq time (us):\t");

	for (i = 0; i < MAX_INTR_STATS; i++)

		seq_printf(s, "%d\t", dwc->irq_completion_time[i]);

	seq_puts(s, "\nevents count:\t\t");

	for (i = 0; i < MAX_INTR_STATS; i++)

		seq_printf(s, "%d\t", dwc->irq_event_count[i]);

	seq_puts(s, "\nbh handled count:\t");

	for (i = 0; i < MAX_INTR_STATS; i++)

		seq_printf(s, "%d\t", dwc->bh_handled_evt_cnt[i]);

	seq_puts(s, "\nirq thread time (us):\t");

	for (i = 0; i < MAX_INTR_STATS; i++)

		seq_printf(s, "%d\t", dwc->bh_completion_time[i]);

	seq_putc(s, '\n');



	spin_unlock_irqrestore(&dwc->lock, flags);

	return 0;

}

drivers/usb/dwc3/gadget.c

+19 −0
Original line number Diff line number Diff line
@@ -3051,6 +3051,7 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt) 
		left -= 4;

	}



	dwc->bh_handled_evt_cnt[dwc->irq_dbg_index] += (evt->count / 4);

	evt->count = 0;

	evt->flags &= ~DWC3_EVENT_PENDING;

	ret = IRQ_HANDLED;
@@ -3074,11 +3075,19 @@ static irqreturn_t dwc3_thread_interrupt(int irq, void *_evt) 
	struct dwc3 *dwc = evt->dwc;

	unsigned long flags;

	irqreturn_t ret = IRQ_NONE;

	ktime_t start_time;



	start_time = ktime_get();



	spin_lock_irqsave(&dwc->lock, flags);

	dwc->bh_handled_evt_cnt[dwc->irq_dbg_index] = 0;

	ret = dwc3_process_event_buf(evt);

	spin_unlock_irqrestore(&dwc->lock, flags);



	dwc->bh_completion_time[dwc->irq_dbg_index] =

		ktime_to_us(ktime_sub(ktime_get(), start_time));

	dwc->irq_dbg_index = (dwc->irq_dbg_index + 1) % MAX_INTR_STATS;



	return ret;

}
@@ -3088,6 +3097,10 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) 
	u32 amount;

	u32 count;

	u32 reg;

	ktime_t start_time;



	start_time = ktime_get();

	dwc->irq_cnt++;



	if (pm_runtime_suspended(dwc->dev)) {

		pm_runtime_get(dwc->dev);
@@ -3126,6 +3139,12 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) 


	dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);



	dwc->irq_start_time[dwc->irq_dbg_index] = start_time;

	dwc->irq_completion_time[dwc->irq_dbg_index] =

		ktime_us_delta(ktime_get(), start_time);

	dwc->irq_event_count[dwc->irq_dbg_index] = count / 4;

	dwc->irq_dbg_index = (dwc->irq_dbg_index + 1) % MAX_INTR_STATS;



	return IRQ_WAKE_THREAD;

}