linux-kernel - [PATCH] drm/sti: Use 64-bit timestamps

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Date:	Wed, 13 Apr 2016 02:28:02 -0700
From:	Tina Ruchandani <ruchandani.tina@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	y2038@...ts.linaro.org,
	Benjamin Gaignard <benjamin.gaignard@...aro.org>,
	Vincent Abriou <vincent.abriou@...com>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/sti: Use 64-bit timestamps

'struct timespec' uses a 32-bit field for seconds, which
will overflow in year 2038 and beyond. This patch is part
of a larger attempt to remove instances of timeval, timespec
and time_t, all of which suffer from the y2038 issue, from the
kernel.

Signed-off-by: Tina Ruchandani <ruchandani.tina@...il.com>
---
 drivers/gpu/drm/sti/sti_plane.c | 16 +++-------------
 drivers/gpu/drm/sti/sti_plane.h |  2 +-
 2 files changed, 4 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/sti/sti_plane.c b/drivers/gpu/drm/sti/sti_plane.c
index f10c98d..3b46899 100644
--- a/drivers/gpu/drm/sti/sti_plane.c
+++ b/drivers/gpu/drm/sti/sti_plane.c
@@ -45,25 +45,15 @@ const char *sti_plane_to_str(struct sti_plane *plane)

 #define STI_FPS_INTERVAL_MS     3000

-static int sti_plane_timespec_ms_diff(struct timespec lhs, struct timespec rhs)
-{
-	struct timespec tmp_ts = timespec_sub(lhs, rhs);
-	u64 tmp_ns = (u64)timespec_to_ns(&tmp_ts);
-
-	do_div(tmp_ns, NSEC_PER_MSEC);
-
-	return (u32)tmp_ns;
-}
-
 void sti_plane_update_fps(struct sti_plane *plane,
 			  bool new_frame,
 			  bool new_field)
 {
-	struct timespec now;
+	ktime_t now;
 	struct sti_fps_info *fps;
 	int fpks, fipks, ms_since_last, num_frames, num_fields;

-	getrawmonotonic(&now);
+	now = ktime_get();

 	/* Compute number of frame updates */
 	fps = &plane->fps_info;
@@ -76,7 +66,7 @@ void sti_plane_update_fps(struct sti_plane *plane,
 		return;

 	fps->curr_frame_counter++;
-	ms_since_last = sti_plane_timespec_ms_diff(now, fps->last_timestamp);
+	ms_since_last = ktime_to_ms(ktime_sub(now, fps->last_timestamp));
 	num_frames = fps->curr_frame_counter - fps->last_frame_counter;

 	if (num_frames <= 0  || ms_since_last < STI_FPS_INTERVAL_MS)
diff --git a/drivers/gpu/drm/sti/sti_plane.h b/drivers/gpu/drm/sti/sti_plane.h
index c50a3b9..0a64eb0 100644
--- a/drivers/gpu/drm/sti/sti_plane.h
+++ b/drivers/gpu/drm/sti/sti_plane.h
@@ -57,7 +57,7 @@ struct sti_fps_info {
 	unsigned int last_frame_counter;
 	unsigned int curr_field_counter;
 	unsigned int last_field_counter;
-	struct timespec last_timestamp;
+	ktime_t	     last_timestamp;
 	char fps_str[FPS_LENGTH];
 	char fips_str[FPS_LENGTH];
 };
--
2.8.0.rc3.226.g39d4020