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Commit 82fde1a9 authored Aug 11, 2015 by Abhilash Jindal Committed by Mauro Carvalho Chehab Aug 16, 2015

[media] bt8xxx: Use monotonic time



Wall time obtained from do_gettimeofday is susceptible to sudden jumps due to
user setting the time or due to NTP.

Monotonic time is constantly increasing time better suited for comparing two
timestamps.

Signed-off-by: Abhilash Jindal <klock.android@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

parent e4d45dd8

drivers/media/pci/bt8xx/bttv-input.c

+8 −13

Original line number	Diff line number	Diff line
		@@ -194,21 +194,18 @@ static u32 bttv_rc5_decode(unsigned int code)
		static void bttv_rc5_timer_end(unsigned long data)
		{
		struct bttv_ir ir = (struct bttv_ir )data;
		struct timeval tv;
		ktime_t tv;
		u32 gap, rc5, scancode;
		u8 toggle, command, system;

		/* get time */
		do_gettimeofday(&tv);
		tv = ktime_get();

		gap = ktime_to_us(ktime_sub(tv, ir->base_time));
		/* avoid overflow with gap >1s */
		if (tv.tv_sec - ir->base_time.tv_sec > 1) {
		if (gap > USEC_PER_SEC) {
		gap = 200000;
		} else {
		gap = 1000000 * (tv.tv_sec - ir->base_time.tv_sec) +
		tv.tv_usec - ir->base_time.tv_usec;
		}

		/* signal we're ready to start a new code */
		ir->active = false;

		@@ -249,7 +246,7 @@ static void bttv_rc5_timer_end(unsigned long data)
		static int bttv_rc5_irq(struct bttv *btv)
		{
		struct bttv_ir *ir = btv->remote;
		struct timeval tv;
		ktime_t tv;
		u32 gpio;
		u32 gap;
		unsigned long current_jiffies;
		@@ -259,14 +256,12 @@ static int bttv_rc5_irq(struct bttv *btv)

		/* get time of bit */
		current_jiffies = jiffies;
		do_gettimeofday(&tv);
		tv = ktime_get();

		gap = ktime_to_us(ktime_sub(tv, ir->base_time));
		/* avoid overflow with gap >1s */
		if (tv.tv_sec - ir->base_time.tv_sec > 1) {
		if (gap > USEC_PER_SEC) {
		gap = 200000;
		} else {
		gap = 1000000 * (tv.tv_sec - ir->base_time.tv_sec) +
		tv.tv_usec - ir->base_time.tv_usec;
		}

		dprintk("RC5 IRQ: gap %d us for %s\n",

drivers/media/pci/bt8xx/bttvp.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -140,7 +140,7 @@ struct bttv_ir {
		bool rc5_gpio; /* Is RC5 legacy GPIO enabled? */
		u32 last_bit; /* last raw bit seen */
		u32 code; /* raw code under construction */
		struct timeval base_time; /* time of last seen code */
		ktime_t base_time; /* time of last seen code */
		bool active; /* building raw code */
		};