[PATCH v3] Staging: olpc_dcon: Replace timespec with ktime_t

[PATCH v3] Staging: olpc_dcon: Replace timespec with ktime_t

[Ksenija Stanojevic]

Struct timespec will overflow in year 2038, here it will not cause an
overflow because it is used with timespec_sub, but still has to be
removed as part of y2038 changes. Replace it with ktime_t. Also use
monotonic instead of real-time by replacing functions getnstimeofday
with ktime_get.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
---
Changes in v3:
        -fix commit message (ktime_sub -> ktime_get)

Changes in v2:
        -use ktime_t instead timespec64
        -use ktime_sub instead timespec64_sub
        -use monotonic instead real-time.

 drivers/staging/olpc_dcon/olpc_dcon.c | 27 +++++++++++++--------------
 drivers/staging/olpc_dcon/olpc_dcon.h |  4 ++--
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/drivers/staging/olpc_dcon/olpc_dcon.c b/drivers/staging/olpc_dcon/olpc_dcon.c
index d115f5c..2dc5d36 100644
--- a/drivers/staging/olpc_dcon/olpc_dcon.c
+++ b/drivers/staging/olpc_dcon/olpc_dcon.c
@@ -238,13 +238,12 @@ static void dcon_sleep(struct dcon_priv *dcon, bool sleep)
  */
 static void dcon_load_holdoff(struct dcon_priv *dcon)
 {
-	struct timespec delta_t, now;
+	ktime_t delta_t, now;
 
 	while (1) {
-		getnstimeofday(&now);
-		delta_t = timespec_sub(now, dcon->load_time);
-		if (delta_t.tv_sec != 0 ||
-			delta_t.tv_nsec > NSEC_PER_MSEC * 20) {
+		now = ktime_get();
+		delta_t = ktime_sub(now, dcon->load_time);
+		if (ktime_to_ns(delta_t) > NSEC_PER_MSEC * 20) {
 			break;
 		}
 		mdelay(4);
@@ -325,19 +324,19 @@ static void dcon_source_switch(struct work_struct *work)
 
 		/* And turn off the DCON */
 		pdata->set_dconload(1);
-		getnstimeofday(&dcon->load_time);
+		dcon->load_time = ktime_get();
 
 		pr_info("The CPU has control\n");
 		break;
 	case DCON_SOURCE_DCON:
 	{
-		struct timespec delta_t;
+		ktime_t delta_t;
 
 		pr_info("dcon_source_switch to DCON\n");
 
 		/* Clear DCONLOAD - this implies that the DCON is in control */
 		pdata->set_dconload(0);
-		getnstimeofday(&dcon->load_time);
+		dcon->load_time = ktime_get();
 
 		wait_event_timeout(dcon->waitq, dcon->switched, HZ/2);
 
@@ -355,14 +354,14 @@ static void dcon_source_switch(struct work_struct *work)
 			 * deassert and reassert, and hope for the best.
 			 * see http://dev.laptop.org/ticket/9664
 			 */
-			delta_t = timespec_sub(dcon->irq_time, dcon->load_time);
-			if (dcon->switched && delta_t.tv_sec == 0 &&
-					delta_t.tv_nsec < NSEC_PER_MSEC * 20) {
+			delta_t = ktime_sub(dcon->irq_time, dcon->load_time);
+			if (dcon->switched && 
+				ktime_to_ns(delta_t) < NSEC_PER_MSEC * 20) {
 				pr_err("missed loading, retrying\n");
 				pdata->set_dconload(1);
 				mdelay(41);
 				pdata->set_dconload(0);
-				getnstimeofday(&dcon->load_time);
+				dcon->load_time = ktime_get();
 				mdelay(41);
 			}
 		}
@@ -742,7 +741,7 @@ irqreturn_t dcon_interrupt(int irq, void *id)
 	case 2:	/* switch to DCON mode */
 	case 1: /* switch to CPU mode */
 		dcon->switched = true;
-		getnstimeofday(&dcon->irq_time);
+		dcon->irq_time = ktime_get();
 		wake_up(&dcon->waitq);
 		break;
 
@@ -756,7 +755,7 @@ irqreturn_t dcon_interrupt(int irq, void *id)
 		 */
 		if (dcon->curr_src != dcon->pending_src && !dcon->switched) {
 			dcon->switched = true;
-			getnstimeofday(&dcon->irq_time);
+			dcon->irq_time = ktime_get();
 			wake_up(&dcon->waitq);
 			pr_debug("switching w/ status 0/0\n");
 		} else {
diff --git a/drivers/staging/olpc_dcon/olpc_dcon.h b/drivers/staging/olpc_dcon/olpc_dcon.h
index d06e19d..215e7ec 100644
--- a/drivers/staging/olpc_dcon/olpc_dcon.h
+++ b/drivers/staging/olpc_dcon/olpc_dcon.h
@@ -79,8 +79,8 @@ struct dcon_priv {
 
 	/* Variables used during switches */
 	bool switched;
-	struct timespec irq_time;
-	struct timespec load_time;
+	ktime_t irq_time;
+	ktime_t load_time;
 
 	/* Current output type; true == mono, false == color */
 	bool mono;
-- 
1.9.1

Re: [Y2038] [PATCH v3] Staging: olpc_dcon: Replace timespec with ktime_t

[Arnd Bergmann]

On Thursday 01 October 2015 17:29:00 Ksenija Stanojevic wrote:
> Struct timespec will overflow in year 2038, here it will not cause an
> overflow because it is used with timespec_sub, but still has to be
> removed as part of y2038 changes. Replace it with ktime_t. Also use
> monotonic instead of real-time by replacing functions getnstimeofday
> with ktime_get.
> 
> Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
> 

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

Re: [Outreachy kernel] [PATCH v3] Staging: olpc_dcon: Replace timespec with ktime_t

[Sudip Mukherjee]

On Thu, Oct 01, 2015 at 05:29:00PM +0200, Ksenija Stanojevic wrote:
> Struct timespec will overflow in year 2038, here it will not cause an
> overflow because it is used with timespec_sub, but still has to be
> removed as part of y2038 changes. Replace it with ktime_t. Also use
> monotonic instead of real-time by replacing functions getnstimeofday
> with ktime_get.
> 
> Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
> ---
Please always test your patch with checkpatch before sending. It has
trailing whitespace.
>
<snip>
> @@ -355,14 +354,14 @@ static void dcon_source_switch(struct work_struct *work)
>  			 * deassert and reassert, and hope for the best.
>  			 * see http://dev.laptop.org/ticket/9664
>  			 */
> -			delta_t = timespec_sub(dcon->irq_time, dcon->load_time);
> -			if (dcon->switched && delta_t.tv_sec == 0 &&
> -					delta_t.tv_nsec < NSEC_PER_MSEC * 20) {
> +			delta_t = ktime_sub(dcon->irq_time, dcon->load_time);
> +			if (dcon->switched && 
whitespace error here.

regards
sudip