media: staging: imx: use ktime_t for timestamps

The imx media driver passes around monotonic timestamps in the deprecated
'timespec' format. This is not a problem for the driver, as they won't
overflow, but moving to either timespec64 or ktime_t is preferred.

I'm picking ktime_t for simplicity here. frame_interval_monitor() is
the main function that changes, as it tries to compare a time interval
in microseconds. The algorithm slightly changes here, to avoid 64-bit
division. The code previously assumed that the error was at most 32-bit
worth of microseconds here, so I'm making the same assumption but add
an explicit test for it.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
index ebb4ca530de2efe48adebf8ed2d27b63db3ca608..f4a3bf5ca2bbc5084a09d3098f03e3ff7a07b642 100644 (file)
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -207,13 +207,9 @@ static irqreturn_t csi_idmac_eof_interrupt(int irq, void *dev_id)
                goto unlock;
        }
 
-       if (priv->fim) {
-               struct timespec cur_ts;
-
-               ktime_get_ts(&cur_ts);
+       if (priv->fim)
                /* call frame interval monitor */
-               imx_media_fim_eof_monitor(priv->fim, &cur_ts);
-       }
+               imx_media_fim_eof_monitor(priv->fim, ktime_get());
 
        csi_vb2_buf_done(priv);
 

diff --git a/drivers/staging/media/imx/imx-media-fim.c b/drivers/staging/media/imx/imx-media-fim.c
index 47275ef803f3515742e3adc6fd614390c0487e4e..6df189135db88c84b0a9acdd3e613452423440f2 100644 (file)
--- a/drivers/staging/media/imx/imx-media-fim.c
+++ b/drivers/staging/media/imx/imx-media-fim.c
@@ -66,7 +66,7 @@ struct imx_media_fim {
        int               icap_flags;
 
        int               counter;
-       struct timespec   last_ts;
+       ktime_t           last_ts;
        unsigned long     sum;       /* usec */
        unsigned long     nominal;   /* usec */
 
@@ -147,22 +147,26 @@ static void send_fim_event(struct imx_media_fim *fim, unsigned long error)
  * (presumably random) interrupt latency.
  */
 static void frame_interval_monitor(struct imx_media_fim *fim,
-                                  struct timespec *ts)
+                                  ktime_t timestamp)
 {
-       unsigned long interval, error, error_avg;
+       long long interval, error;
+       unsigned long error_avg;
        bool send_event = false;
-       struct timespec diff;
 
        if (!fim->enabled || ++fim->counter <= 0)
                goto out_update_ts;
 
-       diff = timespec_sub(*ts, fim->last_ts);
-       interval = diff.tv_sec * 1000 * 1000 + diff.tv_nsec / 1000;
-       error = abs(interval - fim->nominal);
+       /* max error is less than l00µs, so use 32-bit division or fail */
+       interval = ktime_to_ns(ktime_sub(timestamp, fim->last_ts));
+       error = abs(interval - NSEC_PER_USEC * (u64)fim->nominal);
+       if (error > U32_MAX)
+               error = U32_MAX;
+       else
+               error = abs((u32)error / NSEC_PER_USEC);
 
        if (fim->tolerance_max && error >= fim->tolerance_max) {
                dev_dbg(fim->sd->dev,
-                       "FIM: %lu ignored, out of tolerance bounds\n",
+                       "FIM: %llu ignored, out of tolerance bounds\n",
                        error);
                fim->counter--;
                goto out_update_ts;
@@ -184,7 +188,7 @@ static void frame_interval_monitor(struct imx_media_fim *fim,
        }
 
 out_update_ts:
-       fim->last_ts = *ts;
+       fim->last_ts = timestamp;
        if (send_event)
                send_fim_event(fim, error_avg);
 }
@@ -195,14 +199,14 @@ out_update_ts:
  * to interrupt latency.
  */
 static void fim_input_capture_handler(int channel, void *dev_id,
-                                     struct timespec *ts)
+                                     ktime_t timestamp)
 {
        struct imx_media_fim *fim = dev_id;
        unsigned long flags;
 
        spin_lock_irqsave(&fim->lock, flags);
 
-       frame_interval_monitor(fim, ts);
+       frame_interval_monitor(fim, timestamp);
 
        if (!completion_done(&fim->icap_first_event))
                complete(&fim->icap_first_event);
@@ -405,14 +409,14 @@ err_free:
  * the frame_interval_monitor() is called by the input capture event
  * callback handler in that case.
  */
-void imx_media_fim_eof_monitor(struct imx_media_fim *fim, struct timespec *ts)
+void imx_media_fim_eof_monitor(struct imx_media_fim *fim, ktime_t timestamp)
 {
        unsigned long flags;
 
        spin_lock_irqsave(&fim->lock, flags);
 
        if (!icap_enabled(fim))
-               frame_interval_monitor(fim, ts);
+               frame_interval_monitor(fim, timestamp);
 
        spin_unlock_irqrestore(&fim->lock, flags);
 }

diff --git a/drivers/staging/media/imx/imx-media.h b/drivers/staging/media/imx/imx-media.h
index e5b8d2953be52547edc2a52598dd231cdb2ed20d..a5ae0baa5e19c1e5e703a6af83a2f82f065d16c9 100644 (file)
--- a/drivers/staging/media/imx/imx-media.h
+++ b/drivers/staging/media/imx/imx-media.h
@@ -280,7 +280,7 @@ int imx_media_pipeline_set_stream(struct imx_media_dev *imxmd,
 
 /* imx-media-fim.c */
 struct imx_media_fim;
-void imx_media_fim_eof_monitor(struct imx_media_fim *fim, struct timespec *ts);
+void imx_media_fim_eof_monitor(struct imx_media_fim *fim, ktime_t timestamp);
 int imx_media_fim_set_stream(struct imx_media_fim *fim,
                             const struct v4l2_fract *frame_interval,
                             bool on);