| Message ID | 20171127132027.1734806-8-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Arnd, This looks fine to me, except for a couple things... On 11/27/2017 05:20 AM, Arnd Bergmann wrote: > 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> > --- > drivers/staging/media/imx/imx-media-csi.c | 8 ++------ > drivers/staging/media/imx/imx-media-fim.c | 30 +++++++++++++++++------------- > drivers/staging/media/imx/imx-media.h | 2 +- > 3 files changed, 20 insertions(+), 20 deletions(-) > > diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c > index bb1d6dafca83..26994b429cf2 100644 > --- 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 47275ef803f3..6df189135db8 100644 > --- 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 */ This comment doesn't make sense. By "max error" maybe you are referring to the tolerance_max control, which is limited to 500 usec, but if set to zero (or less than tolerance_min), there is no max error, it is unbounded. Please just remove this comment. > + 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); Why the second abs() ? How about the following: - if (error > U32_MAX) - error = U32_MAX; - else - error = abs((u32)error / NSEC_PER_USEC); + /* convert interval error to usec using 32-bit divide */ + error = (u32)min_t(long long, error, U32_MAX) / NSEC_PER_USEC; Steve > > 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 @@ static void frame_interval_monitor(struct imx_media_fim *fim, > * 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 @@ static int init_fim_controls(struct imx_media_fim *fim) > * 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 d409170632bd..ac3ab115394f 100644 > --- 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);
diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c index bb1d6dafca83..26994b429cf2 100644 --- 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 47275ef803f3..6df189135db8 100644 --- 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 @@ static void frame_interval_monitor(struct imx_media_fim *fim, * 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 @@ static int init_fim_controls(struct imx_media_fim *fim) * 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 d409170632bd..ac3ab115394f 100644 --- 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);
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> --- drivers/staging/media/imx/imx-media-csi.c | 8 ++------ drivers/staging/media/imx/imx-media-fim.c | 30 +++++++++++++++++------------- drivers/staging/media/imx/imx-media.h | 2 +- 3 files changed, 20 insertions(+), 20 deletions(-)