| Message ID | 20211213134940.324266-18-eugen.hristev@microchip.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: atmel: atmel-isc: implement media controller | expand |
Hi Eugen On Mon, Dec 13, 2021 at 03:49:34PM +0200, Eugen Hristev wrote: > The AWB workqueue runs in a kernel thread and needs to be synchronized > w.r.t. the streaming status. > It is possible that streaming is stopped while the AWB workq is running. > In this case it is likely that the check for isc->stop is done at one point > in time, but the AWB computations are done later, including a call to > isc_update_profile, which requires streaming to be started. > Thus , isc_update_profile will fail if during this operation sequence the > streaming was stopped. > To solve this issue, a mutex is added, that will serialize the awb work and > streaming stopping, with the mention that either streaming is stopped > completely including termination of the last frame is done, and after that > the AWB work can check stream status and stop; either first AWB work is > completed and after that the streaming can stop correctly. > The awb spin lock cannot be used since this spinlock is taken in the same > context and using it in the stop streaming will result in a recursion BUG. > > Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com> > --- > drivers/media/platform/atmel/atmel-isc-base.c | 31 ++++++++++++++++--- > drivers/media/platform/atmel/atmel-isc.h | 1 + > 2 files changed, 28 insertions(+), 4 deletions(-) > > diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c > index b0c3ed21f372..53cac1aac0fd 100644 > --- a/drivers/media/platform/atmel/atmel-isc-base.c > +++ b/drivers/media/platform/atmel/atmel-isc-base.c > @@ -401,6 +401,7 @@ static void isc_stop_streaming(struct vb2_queue *vq) > struct isc_buffer *buf; > int ret; > > + mutex_lock(&isc->awb_mutex); > v4l2_ctrl_activate(isc->do_wb_ctrl, false); > > isc->stop = true; > @@ -410,6 +411,8 @@ static void isc_stop_streaming(struct vb2_queue *vq) > v4l2_err(&isc->v4l2_dev, > "Timeout waiting for end of the capture\n"); > > + mutex_unlock(&isc->awb_mutex); > + > /* Disable DMA interrupt */ > regmap_write(isc->regmap, ISC_INTDIS, ISC_INT_DDONE); > > @@ -1416,10 +1419,6 @@ static void isc_awb_work(struct work_struct *w) > u32 min, max; > int ret; > > - /* streaming is not active anymore */ > - if (isc->stop) > - return; > - > if (ctrls->hist_stat != HIST_ENABLED) > return; > > @@ -1470,7 +1469,24 @@ static void isc_awb_work(struct work_struct *w) > } > regmap_write(regmap, ISC_HIS_CFG + isc->offsets.his, > hist_id | baysel | ISC_HIS_CFG_RAR); isc_stop_streaming() calls runtime_put and here you access the hw. Feels like it's safer to hold the mutex for the whole duration of the AWB routine ? > + > + /* > + * We have to make sure the streaming has not stopped meanwhile. > + * ISC requires a frame to clock the internal profile update. > + * To avoid issues, lock the sequence with a mutex > + */ > + mutex_lock(&isc->awb_mutex); > + > + /* streaming is not active anymore */ > + if (isc->stop) { > + mutex_unlock(&isc->awb_mutex); > + return; > + }; > + > isc_update_profile(isc); > + > + mutex_unlock(&isc->awb_mutex); > + > /* if awb has been disabled, we don't need to start another histogram */ > if (ctrls->awb) > regmap_write(regmap, ISC_CTRLEN, ISC_CTRL_HISREQ); > @@ -1549,6 +1565,8 @@ static int isc_s_awb_ctrl(struct v4l2_ctrl *ctrl) > > isc_update_awb_ctrls(isc); > > + mutex_lock(&isc->awb_mutex); > + > if (!isc->stop) { > /* > * If we are streaming, we can update profile to > @@ -1563,6 +1581,7 @@ static int isc_s_awb_ctrl(struct v4l2_ctrl *ctrl) > */ > v4l2_ctrl_activate(isc->do_wb_ctrl, false); > } > + mutex_unlock(&isc->awb_mutex); > > /* if we have autowhitebalance on, start histogram procedure */ > if (ctrls->awb == ISC_WB_AUTO && !isc->stop && > @@ -1754,6 +1773,7 @@ static void isc_async_unbind(struct v4l2_async_notifier *notifier, > { > struct isc_device *isc = container_of(notifier->v4l2_dev, > struct isc_device, v4l2_dev); > + mutex_destroy(&isc->awb_mutex); > cancel_work_sync(&isc->awb_work); > video_unregister_device(&isc->video_dev); > v4l2_ctrl_handler_free(&isc->ctrls.handler); > @@ -1866,6 +1886,8 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier) > isc->current_subdev = container_of(notifier, > struct isc_subdev_entity, notifier); > mutex_init(&isc->lock); > + mutex_init(&isc->awb_mutex); > + > init_completion(&isc->comp); > > /* Initialize videobuf2 queue */ > @@ -1941,6 +1963,7 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier) > video_unregister_device(vdev); > > isc_async_complete_err: > + mutex_destroy(&isc->awb_mutex); > mutex_destroy(&isc->lock); > return ret; > } > diff --git a/drivers/media/platform/atmel/atmel-isc.h b/drivers/media/platform/atmel/atmel-isc.h > index 0b6370d7775f..c2cb805faff3 100644 > --- a/drivers/media/platform/atmel/atmel-isc.h > +++ b/drivers/media/platform/atmel/atmel-isc.h > @@ -307,6 +307,7 @@ struct isc_device { > struct work_struct awb_work; > > struct mutex lock; /* serialize access to file operations */ > + struct mutex awb_mutex; /* serialize access to streaming status from awb work queue */ > spinlock_t awb_lock; /* serialize access to DMA buffers from awb work queue */ > > struct regmap_field *pipeline[ISC_PIPE_LINE_NODE_NUM]; > -- > 2.25.1 >
On 1/12/22 10:58 AM, Jacopo Mondi wrote: > Hi Eugen > > On Mon, Dec 13, 2021 at 03:49:34PM +0200, Eugen Hristev wrote: >> The AWB workqueue runs in a kernel thread and needs to be synchronized >> w.r.t. the streaming status. >> It is possible that streaming is stopped while the AWB workq is running. >> In this case it is likely that the check for isc->stop is done at one point >> in time, but the AWB computations are done later, including a call to >> isc_update_profile, which requires streaming to be started. >> Thus , isc_update_profile will fail if during this operation sequence the >> streaming was stopped. >> To solve this issue, a mutex is added, that will serialize the awb work and >> streaming stopping, with the mention that either streaming is stopped >> completely including termination of the last frame is done, and after that >> the AWB work can check stream status and stop; either first AWB work is >> completed and after that the streaming can stop correctly. >> The awb spin lock cannot be used since this spinlock is taken in the same >> context and using it in the stop streaming will result in a recursion BUG. >> >> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com> >> --- >> drivers/media/platform/atmel/atmel-isc-base.c | 31 ++++++++++++++++--- >> drivers/media/platform/atmel/atmel-isc.h | 1 + >> 2 files changed, 28 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c >> index b0c3ed21f372..53cac1aac0fd 100644 >> --- a/drivers/media/platform/atmel/atmel-isc-base.c >> +++ b/drivers/media/platform/atmel/atmel-isc-base.c >> @@ -401,6 +401,7 @@ static void isc_stop_streaming(struct vb2_queue *vq) >> struct isc_buffer *buf; >> int ret; >> >> + mutex_lock(&isc->awb_mutex); >> v4l2_ctrl_activate(isc->do_wb_ctrl, false); >> >> isc->stop = true; >> @@ -410,6 +411,8 @@ static void isc_stop_streaming(struct vb2_queue *vq) >> v4l2_err(&isc->v4l2_dev, >> "Timeout waiting for end of the capture\n"); >> >> + mutex_unlock(&isc->awb_mutex); >> + >> /* Disable DMA interrupt */ >> regmap_write(isc->regmap, ISC_INTDIS, ISC_INT_DDONE); >> >> @@ -1416,10 +1419,6 @@ static void isc_awb_work(struct work_struct *w) >> u32 min, max; >> int ret; >> >> - /* streaming is not active anymore */ >> - if (isc->stop) >> - return; >> - >> if (ctrls->hist_stat != HIST_ENABLED) >> return; >> >> @@ -1470,7 +1469,24 @@ static void isc_awb_work(struct work_struct *w) >> } >> regmap_write(regmap, ISC_HIS_CFG + isc->offsets.his, >> hist_id | baysel | ISC_HIS_CFG_RAR); > > isc_stop_streaming() calls runtime_put and here you access the hw. Hi Jacopo, That is correct. However the awb routine will call resume and get here (before accessing the hardware) : https://elixir.bootlin.com/linux/latest/source/drivers/media/platform/atmel/atmel-isc-base.c#L1722 So I think that we are good as we are now > > Feels like it's safer to hold the mutex for the whole duration of the > AWB routine ? > I prefer to have the critical section as little as possible. As we are only synchronizing the 'streaming status' , only this should be under the lock. If you have a different opinion, let me know. Eugen >> + >> + /* >> + * We have to make sure the streaming has not stopped meanwhile. >> + * ISC requires a frame to clock the internal profile update. >> + * To avoid issues, lock the sequence with a mutex >> + */ >> + mutex_lock(&isc->awb_mutex); >> + >> + /* streaming is not active anymore */ >> + if (isc->stop) { >> + mutex_unlock(&isc->awb_mutex); >> + return; >> + }; >> + >> isc_update_profile(isc); >> + >> + mutex_unlock(&isc->awb_mutex); >> + >> /* if awb has been disabled, we don't need to start another histogram */ >> if (ctrls->awb) >> regmap_write(regmap, ISC_CTRLEN, ISC_CTRL_HISREQ); >> @@ -1549,6 +1565,8 @@ static int isc_s_awb_ctrl(struct v4l2_ctrl *ctrl) >> >> isc_update_awb_ctrls(isc); >> >> + mutex_lock(&isc->awb_mutex); >> + >> if (!isc->stop) { >> /* >> * If we are streaming, we can update profile to >> @@ -1563,6 +1581,7 @@ static int isc_s_awb_ctrl(struct v4l2_ctrl *ctrl) >> */ >> v4l2_ctrl_activate(isc->do_wb_ctrl, false); >> } >> + mutex_unlock(&isc->awb_mutex); >> >> /* if we have autowhitebalance on, start histogram procedure */ >> if (ctrls->awb == ISC_WB_AUTO && !isc->stop && >> @@ -1754,6 +1773,7 @@ static void isc_async_unbind(struct v4l2_async_notifier *notifier, >> { >> struct isc_device *isc = container_of(notifier->v4l2_dev, >> struct isc_device, v4l2_dev); >> + mutex_destroy(&isc->awb_mutex); >> cancel_work_sync(&isc->awb_work); >> video_unregister_device(&isc->video_dev); >> v4l2_ctrl_handler_free(&isc->ctrls.handler); >> @@ -1866,6 +1886,8 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier) >> isc->current_subdev = container_of(notifier, >> struct isc_subdev_entity, notifier); >> mutex_init(&isc->lock); >> + mutex_init(&isc->awb_mutex); >> + >> init_completion(&isc->comp); >> >> /* Initialize videobuf2 queue */ >> @@ -1941,6 +1963,7 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier) >> video_unregister_device(vdev); >> >> isc_async_complete_err: >> + mutex_destroy(&isc->awb_mutex); >> mutex_destroy(&isc->lock); >> return ret; >> } >> diff --git a/drivers/media/platform/atmel/atmel-isc.h b/drivers/media/platform/atmel/atmel-isc.h >> index 0b6370d7775f..c2cb805faff3 100644 >> --- a/drivers/media/platform/atmel/atmel-isc.h >> +++ b/drivers/media/platform/atmel/atmel-isc.h >> @@ -307,6 +307,7 @@ struct isc_device { >> struct work_struct awb_work; >> >> struct mutex lock; /* serialize access to file operations */ >> + struct mutex awb_mutex; /* serialize access to streaming status from awb work queue */ >> spinlock_t awb_lock; /* serialize access to DMA buffers from awb work queue */ >> >> struct regmap_field *pipeline[ISC_PIPE_LINE_NODE_NUM]; >> -- >> 2.25.1 >>
diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c index b0c3ed21f372..53cac1aac0fd 100644 --- a/drivers/media/platform/atmel/atmel-isc-base.c +++ b/drivers/media/platform/atmel/atmel-isc-base.c @@ -401,6 +401,7 @@ static void isc_stop_streaming(struct vb2_queue *vq) struct isc_buffer *buf; int ret; + mutex_lock(&isc->awb_mutex); v4l2_ctrl_activate(isc->do_wb_ctrl, false); isc->stop = true; @@ -410,6 +411,8 @@ static void isc_stop_streaming(struct vb2_queue *vq) v4l2_err(&isc->v4l2_dev, "Timeout waiting for end of the capture\n"); + mutex_unlock(&isc->awb_mutex); + /* Disable DMA interrupt */ regmap_write(isc->regmap, ISC_INTDIS, ISC_INT_DDONE); @@ -1416,10 +1419,6 @@ static void isc_awb_work(struct work_struct *w) u32 min, max; int ret; - /* streaming is not active anymore */ - if (isc->stop) - return; - if (ctrls->hist_stat != HIST_ENABLED) return; @@ -1470,7 +1469,24 @@ static void isc_awb_work(struct work_struct *w) } regmap_write(regmap, ISC_HIS_CFG + isc->offsets.his, hist_id | baysel | ISC_HIS_CFG_RAR); + + /* + * We have to make sure the streaming has not stopped meanwhile. + * ISC requires a frame to clock the internal profile update. + * To avoid issues, lock the sequence with a mutex + */ + mutex_lock(&isc->awb_mutex); + + /* streaming is not active anymore */ + if (isc->stop) { + mutex_unlock(&isc->awb_mutex); + return; + }; + isc_update_profile(isc); + + mutex_unlock(&isc->awb_mutex); + /* if awb has been disabled, we don't need to start another histogram */ if (ctrls->awb) regmap_write(regmap, ISC_CTRLEN, ISC_CTRL_HISREQ); @@ -1549,6 +1565,8 @@ static int isc_s_awb_ctrl(struct v4l2_ctrl *ctrl) isc_update_awb_ctrls(isc); + mutex_lock(&isc->awb_mutex); + if (!isc->stop) { /* * If we are streaming, we can update profile to @@ -1563,6 +1581,7 @@ static int isc_s_awb_ctrl(struct v4l2_ctrl *ctrl) */ v4l2_ctrl_activate(isc->do_wb_ctrl, false); } + mutex_unlock(&isc->awb_mutex); /* if we have autowhitebalance on, start histogram procedure */ if (ctrls->awb == ISC_WB_AUTO && !isc->stop && @@ -1754,6 +1773,7 @@ static void isc_async_unbind(struct v4l2_async_notifier *notifier, { struct isc_device *isc = container_of(notifier->v4l2_dev, struct isc_device, v4l2_dev); + mutex_destroy(&isc->awb_mutex); cancel_work_sync(&isc->awb_work); video_unregister_device(&isc->video_dev); v4l2_ctrl_handler_free(&isc->ctrls.handler); @@ -1866,6 +1886,8 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier) isc->current_subdev = container_of(notifier, struct isc_subdev_entity, notifier); mutex_init(&isc->lock); + mutex_init(&isc->awb_mutex); + init_completion(&isc->comp); /* Initialize videobuf2 queue */ @@ -1941,6 +1963,7 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier) video_unregister_device(vdev); isc_async_complete_err: + mutex_destroy(&isc->awb_mutex); mutex_destroy(&isc->lock); return ret; } diff --git a/drivers/media/platform/atmel/atmel-isc.h b/drivers/media/platform/atmel/atmel-isc.h index 0b6370d7775f..c2cb805faff3 100644 --- a/drivers/media/platform/atmel/atmel-isc.h +++ b/drivers/media/platform/atmel/atmel-isc.h @@ -307,6 +307,7 @@ struct isc_device { struct work_struct awb_work; struct mutex lock; /* serialize access to file operations */ + struct mutex awb_mutex; /* serialize access to streaming status from awb work queue */ spinlock_t awb_lock; /* serialize access to DMA buffers from awb work queue */ struct regmap_field *pipeline[ISC_PIPE_LINE_NODE_NUM];
The AWB workqueue runs in a kernel thread and needs to be synchronized w.r.t. the streaming status. It is possible that streaming is stopped while the AWB workq is running. In this case it is likely that the check for isc->stop is done at one point in time, but the AWB computations are done later, including a call to isc_update_profile, which requires streaming to be started. Thus , isc_update_profile will fail if during this operation sequence the streaming was stopped. To solve this issue, a mutex is added, that will serialize the awb work and streaming stopping, with the mention that either streaming is stopped completely including termination of the last frame is done, and after that the AWB work can check stream status and stop; either first AWB work is completed and after that the streaming can stop correctly. The awb spin lock cannot be used since this spinlock is taken in the same context and using it in the stop streaming will result in a recursion BUG. Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com> --- drivers/media/platform/atmel/atmel-isc-base.c | 31 ++++++++++++++++--- drivers/media/platform/atmel/atmel-isc.h | 1 + 2 files changed, 28 insertions(+), 4 deletions(-)