Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751980AbdLEAhQ (ORCPT ); Mon, 4 Dec 2017 19:37:16 -0500 Received: from galahad.ideasonboard.com ([185.26.127.97]:41163 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750995AbdLEAhO (ORCPT ); Mon, 4 Dec 2017 19:37:14 -0500 From: Laurent Pinchart To: Arnd Bergmann Cc: Mauro Carvalho Chehab , y2038@lists.linaro.org, Kieran Bingham , Guennadi Liakhovetski , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/8] [media] uvc_video: use ktime_t for timestamps Date: Tue, 05 Dec 2017 02:37:27 +0200 Message-ID: <2878836.BpTQ5Kp5iv@avalon> Organization: Ideas on Board Oy In-Reply-To: <20171127132027.1734806-2-arnd@arndb.de> References: <20171127132027.1734806-1-arnd@arndb.de> <20171127132027.1734806-2-arnd@arndb.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5924 Lines: 174 Hi Arnd, Thank you for the patch. On Monday, 27 November 2017 15:19:54 EET Arnd Bergmann wrote: > uvc_video_get_ts() returns a 'struct timespec', but all its users > really want a nanoseconds variable anyway. > > Changing the deprecated ktime_get_ts/ktime_get_real_ts to ktime_get > and ktime_get_real simplifies the code noticeably, while keeping > the resulting numbers unchanged. > > Signed-off-by: Arnd Bergmann > --- > drivers/media/usb/uvc/uvc_video.c | 37 ++++++++++++----------------------- > drivers/media/usb/uvc/uvcvideo.h | 2 +- > 2 files changed, 13 insertions(+), 26 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_video.c > b/drivers/media/usb/uvc/uvc_video.c index d6bee37cd1b8..f7a919490b2b 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -369,12 +369,12 @@ static int uvc_commit_video(struct uvc_streaming > *stream, * Clocks and timestamps > */ > > -static inline void uvc_video_get_ts(struct timespec *ts) > +static inline ktime_t uvc_video_get_time(void) > { > if (uvc_clock_param == CLOCK_MONOTONIC) > - ktime_get_ts(ts); > + return ktime_get(); > else > - ktime_get_real_ts(ts); > + return ktime_get_real(); > } > > static void > @@ -386,7 +386,7 @@ uvc_video_clock_decode(struct uvc_streaming *stream, > struct uvc_buffer *buf, bool has_pts = false; > bool has_scr = false; > unsigned long flags; > - struct timespec ts; > + ktime_t time; > u16 host_sof; > u16 dev_sof; > > @@ -436,7 +436,7 @@ uvc_video_clock_decode(struct uvc_streaming *stream, > struct uvc_buffer *buf, stream->clock.last_sof = dev_sof; > > host_sof = usb_get_current_frame_number(stream->dev->udev); > - uvc_video_get_ts(&ts); > + time = uvc_video_get_time(); > > /* The UVC specification allows device implementations that can't obtain > * the USB frame number to keep their own frame counters as long as they > @@ -473,7 +473,7 @@ uvc_video_clock_decode(struct uvc_streaming *stream, > struct uvc_buffer *buf, sample->dev_stc = > get_unaligned_le32(&data[header_size - 6]); > sample->dev_sof = dev_sof; > sample->host_sof = host_sof; > - sample->host_ts = ts; > + sample->host_time = time; > > /* Update the sliding window head and count. */ > stream->clock.head = (stream->clock.head + 1) % stream->clock.size; > @@ -613,14 +613,12 @@ void uvc_video_clock_update(struct uvc_streaming > *stream, struct uvc_clock_sample *first; > struct uvc_clock_sample *last; > unsigned long flags; > - struct timespec ts; > + u64 timestamp; > u32 delta_stc; > u32 y1, y2; > u32 x1, x2; > u32 mean; > u32 sof; > - u32 div; > - u32 rem; > u64 y; > > if (!uvc_hw_timestamps_param) > @@ -667,9 +665,8 @@ void uvc_video_clock_update(struct uvc_streaming > *stream, if (x1 == x2) > goto done; > > - ts = timespec_sub(last->host_ts, first->host_ts); > y1 = NSEC_PER_SEC; > - y2 = (ts.tv_sec + 1) * NSEC_PER_SEC + ts.tv_nsec; > + y2 = (u32)ktime_to_ns(ktime_sub(last->host_time, first->host_time)) + y1; > > /* Interpolated and host SOF timestamps can wrap around at slightly > * different times. Handle this by adding or removing 2048 to or from > @@ -686,24 +683,18 @@ void uvc_video_clock_update(struct uvc_streaming > *stream, - (u64)y2 * (u64)x1; > y = div_u64(y, x2 - x1); > > - div = div_u64_rem(y, NSEC_PER_SEC, &rem); > - ts.tv_sec = first->host_ts.tv_sec - 1 + div; > - ts.tv_nsec = first->host_ts.tv_nsec + rem; > - if (ts.tv_nsec >= NSEC_PER_SEC) { > - ts.tv_sec++; > - ts.tv_nsec -= NSEC_PER_SEC; > - } > + timestamp = ktime_to_ns(first->host_time) + y - y1; It took me a few minutes to see that the -1 and -y1 were equivalent. And then more time to re-read the code and the comments to understand what I had done. I'm impressed that you haven't blindly replaced the +1s and -1s by +NSEC_PER_SEC and -NSEC_PER_SEC, but used +y1 and -y1 which I think improves readability. Reviewed-by: Laurent Pinchart with the highest honors :-) Should I merge this through my tree ? > uvc_trace(UVC_TRACE_CLOCK, "%s: SOF %u.%06llu y %llu ts %llu " > "buf ts %llu (x1 %u/%u/%u x2 %u/%u/%u y1 %u y2 %u)\n", > stream->dev->name, > sof >> 16, div_u64(((u64)sof & 0xffff) * 1000000LLU, 65536), > - y, timespec_to_ns(&ts), vbuf->vb2_buf.timestamp, > + y, timestamp, vbuf->vb2_buf.timestamp, > x1, first->host_sof, first->dev_sof, > x2, last->host_sof, last->dev_sof, y1, y2); > > /* Update the V4L2 buffer. */ > - vbuf->vb2_buf.timestamp = timespec_to_ns(&ts); > + vbuf->vb2_buf.timestamp = timestamp; > > done: > spin_unlock_irqrestore(&clock->lock, flags); > @@ -1007,8 +998,6 @@ static int uvc_video_decode_start(struct uvc_streaming > *stream, * when the EOF bit is set to force synchronisation on the next > packet. */ > if (buf->state != UVC_BUF_STATE_ACTIVE) { > - struct timespec ts; > - > if (fid == stream->last_fid) { > uvc_trace(UVC_TRACE_FRAME, "Dropping payload (out of " > "sync).\n"); > @@ -1018,11 +1007,9 @@ static int uvc_video_decode_start(struct > uvc_streaming *stream, return -ENODATA; > } > > - uvc_video_get_ts(&ts); > - > buf->buf.field = V4L2_FIELD_NONE; > buf->buf.sequence = stream->sequence; > - buf->buf.vb2_buf.timestamp = timespec_to_ns(&ts); > + buf->buf.vb2_buf.timestamp = uvc_video_get_time(); > > /* TODO: Handle PTS and SCR. */ > buf->state = UVC_BUF_STATE_ACTIVE; > diff --git a/drivers/media/usb/uvc/uvcvideo.h > b/drivers/media/usb/uvc/uvcvideo.h index a2c190937067..d7797dfb6468 100644 > --- a/drivers/media/usb/uvc/uvcvideo.h > +++ b/drivers/media/usb/uvc/uvcvideo.h > @@ -536,8 +536,8 @@ struct uvc_streaming { > struct uvc_clock_sample { > u32 dev_stc; > u16 dev_sof; > - struct timespec host_ts; > u16 host_sof; > + ktime_t host_time; > } *samples; > > unsigned int head; -- Regards, Laurent Pinchart