| Message ID | 1312984992-19315-1-git-send-email-deepthy.ravi@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi, On Wednesday 10 August 2011 16:03:12 Deepthy Ravi wrote: > From: Abhilash K V <abhilash.kv@ti.com> > > While resuming from the "suspended to memory" state, > occasionally CCDC fails to get enabled and thus fails > to capture frames any more till the next suspend/resume > is issued. > This is a race condition which happens only when a CCDC > frame-completion ISR is pending even as ISP device's > isp_pm_prepare() is getting called and only one buffer > is left on the DMA queue. > The DMA queue buffers are thus depleted which results in > its underrun.So when ISP resumes there are no buffers on > the queue (as the application which can issue buffers is > yet to resume) to start video capture. > This fix addresses this issue by dequeuing and enqueing > the last buffer in isp_pm_prepare() after its DMA gets > completed. Thus,when ISP resumes it always finds atleast > one buffer on the DMA queue - this is true if application > uses only 3 buffers. How is that problem specific to the CCDC ? Can't it be reproduce at the preview engine or resizer output as well ?
On Tue, Aug 30, 2011 Laurent Pinchart wrote: > Hi, > > On Wednesday 10 August 2011 16:03:12 Deepthy Ravi wrote: >> From: Abhilash K V <abhilash.kv@ti.com> >> >> While resuming from the "suspended to memory" state, >> occasionally CCDC fails to get enabled and thus fails >> to capture frames any more till the next suspend/resume >> is issued. >> This is a race condition which happens only when a CCDC >> frame-completion ISR is pending even as ISP device's >> isp_pm_prepare() is getting called and only one buffer >> is left on the DMA queue. >> The DMA queue buffers are thus depleted which results in >> its underrun.So when ISP resumes there are no buffers on >> the queue (as the application which can issue buffers is >> yet to resume) to start video capture. >> This fix addresses this issue by dequeuing and enqueing >> the last buffer in isp_pm_prepare() after its DMA gets >> completed. Thus,when ISP resumes it always finds atleast >> one buffer on the DMA queue - this is true if application >> uses only 3 buffers. > > How is that problem specific to the CCDC ? Can't it be reproduce at the > preview engine or resizer output as well ? [Abhilash K V]Yes, I believe this issue would crop with preview and resizer too though I have not been able to try these out. > > -- > Regards, > > Laurent Pinchart > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Wednesday 07 September 2011 12:10:23 Koyamangalath, Abhilash wrote: > On Tue, Aug 30, 2011 Laurent Pinchart wrote: > > On Wednesday 10 August 2011 16:03:12 Deepthy Ravi wrote: > >> From: Abhilash K V <abhilash.kv@ti.com> > >> > >> While resuming from the "suspended to memory" state, > >> occasionally CCDC fails to get enabled and thus fails > >> to capture frames any more till the next suspend/resume > >> is issued. > >> This is a race condition which happens only when a CCDC > >> frame-completion ISR is pending even as ISP device's > >> isp_pm_prepare() is getting called and only one buffer > >> is left on the DMA queue. > >> The DMA queue buffers are thus depleted which results in > >> its underrun.So when ISP resumes there are no buffers on > >> the queue (as the application which can issue buffers is > >> yet to resume) to start video capture. > >> This fix addresses this issue by dequeuing and enqueing > >> the last buffer in isp_pm_prepare() after its DMA gets > >> completed. Thus,when ISP resumes it always finds atleast > >> one buffer on the DMA queue - this is true if application > >> uses only 3 buffers. > > > > How is that problem specific to the CCDC ? Can't it be reproduce at the > > preview engine or resizer output as well ? > > Yes, I believe this issue would crop with preview and resizer too though I > have not been able to try these out. That's my belief as well. In that case the fix should be generic, not CCDC- specific.
diff --git a/drivers/media/video/omap3isp/isp.c b/drivers/media/video/omap3isp/isp.c index 94b6ed8..6604fbd 100644 --- a/drivers/media/video/omap3isp/isp.c +++ b/drivers/media/video/omap3isp/isp.c @@ -1566,8 +1566,20 @@ static int isp_pm_prepare(struct device *dev) { struct isp_device *isp = dev_get_drvdata(dev); int reset; + int err = 0; + struct isp_ccdc_device *ccdc = &isp->isp_ccdc; + struct isp_video *video = &ccdc->video_out; + struct isp_pipeline *pipe = to_isp_pipeline(&video->video.entity); + unsigned long flags; WARN_ON(mutex_is_locked(&isp->isp_mutex)); + spin_lock_irqsave(&pipe->lock, flags); + pipe->state |= ISP_PIPELINE_PREPARE_SUSPEND; + spin_unlock_irqrestore(&pipe->lock, flags); + + err = isp_video_handle_buffer_starvation(video); + if (err < 0) + return err; if (isp->ref_count == 0) return 0; @@ -1596,6 +1608,14 @@ static int isp_pm_suspend(struct device *dev) static int isp_pm_resume(struct device *dev) { struct isp_device *isp = dev_get_drvdata(dev); + struct isp_ccdc_device *ccdc = &isp->isp_ccdc; + struct isp_video *video = &ccdc->video_out; + struct isp_pipeline *pipe = to_isp_pipeline(&video->video.entity); + unsigned long flags; + + spin_lock_irqsave(&pipe->lock, flags); + pipe->state &= ~ISP_PIPELINE_PREPARE_SUSPEND; + spin_unlock_irqrestore(&pipe->lock, flags); if (isp->ref_count == 0) return 0; diff --git a/drivers/media/video/omap3isp/isp.h b/drivers/media/video/omap3isp/isp.h index 841870f..e391974 100644 --- a/drivers/media/video/omap3isp/isp.h +++ b/drivers/media/video/omap3isp/isp.h @@ -349,6 +349,10 @@ int omap3isp_register_entities(struct platform_device *pdev, struct v4l2_device *v4l2_dev); void omap3isp_unregister_entities(struct platform_device *pdev); +#ifdef CONFIG_PM +int isp_video_handle_buffer_starvation(struct isp_video *video); +#endif + /* * isp_reg_readl - Read value of an OMAP3 ISP register * @dev: Device pointer specific to the OMAP3 ISP. diff --git a/drivers/media/video/omap3isp/ispvideo.c b/drivers/media/video/omap3isp/ispvideo.c index 5833a0e..bf149a7 100644 --- a/drivers/media/video/omap3isp/ispvideo.c +++ b/drivers/media/video/omap3isp/ispvideo.c @@ -523,6 +523,26 @@ static int isp_video_buffer_prepare(struct isp_video_buffer *buf) return 0; } +#ifdef CONFIG_PM +static int isp_video_deq_enq(struct isp_video_queue *queue) +{ + int err = 0; + struct v4l2_buffer vbuf; + + vbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE; + /* blocking dequeue to ensure DMA is done */ + err = omap3isp_video_queue_dqbuf(queue, &vbuf, 0); + if (err < 0) + return err; + else { + err = omap3isp_video_queue_qbuf(queue, &vbuf); + if (err < 0) + return err; + } + return err; +} +#endif + /* * isp_video_buffer_queue - Add buffer to streaming queue * @buf: Video buffer @@ -546,7 +566,7 @@ static void isp_video_buffer_queue(struct isp_video_buffer *buf) empty = list_empty(&video->dmaqueue); list_add_tail(&buffer->buffer.irqlist, &video->dmaqueue); - if (empty) { + if (empty && !(pipe->state & ISP_PIPELINE_PREPARE_SUSPEND)) { if (video->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) state = ISP_PIPELINE_QUEUE_OUTPUT; else @@ -687,6 +707,40 @@ void omap3isp_video_resume(struct isp_video *video, int continuous) } } +#ifdef CONFIG_PM + +/* + * isp_video_handle_buffer_starvation - Handles the case when there are only 1 + * or less active buffers present on the dmaqueue while preparing for suspend. + * + * @video: ISP video object + * + * This function is intended to be used in suspend/resume scenario. While + * preparing for suspend, if the number of active buffers on dmaqueue is 0 or 1, + * the last buffer is dequeued after DMA completes and re-queued again. This + * prevents ISP_VIDEO_DMAQUEUE_UNDERRUN from occuring on issue of resume. + */ +int isp_video_handle_buffer_starvation(struct isp_video *video) +{ + int err = 0; + struct isp_video_queue *queue = video->queue; + struct isp_video_buffer *buf; + struct list_head *head = &video->dmaqueue; + + if (list_empty(&video->dmaqueue)) { + err = isp_video_deq_enq(queue); + } else if (head->next->next == head) { + /* only one buffer is left on dmaqueue */ + buf = list_first_entry(&video->dmaqueue, + struct isp_video_buffer, + irqlist); + if (buf->state == ISP_BUF_STATE_ACTIVE) + err = isp_video_deq_enq(queue); + } + return err; +} +#endif + /* ----------------------------------------------------------------------------- * V4L2 ioctls */ diff --git a/drivers/media/video/omap3isp/ispvideo.h b/drivers/media/video/omap3isp/ispvideo.h index 6f203aa..cf209f3 100644 --- a/drivers/media/video/omap3isp/ispvideo.h +++ b/drivers/media/video/omap3isp/ispvideo.h @@ -84,6 +84,8 @@ enum isp_pipeline_state { ISP_PIPELINE_IDLE_OUTPUT = 32, /* The pipeline is currently streaming. */ ISP_PIPELINE_STREAM = 64, + /* The pipeline is currently preparing to suspend. */ + ISP_PIPELINE_PREPARE_SUSPEND = 128, }; struct isp_pipeline {