| Message ID | 20190106212018.16519-1-slongerbeam@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RFC,v2] media: rcar-vin: Allow independent VIN link enablement | expand |
Hi Steve, Thanks for your patch, I think it looks good. On 2019-01-06 13:20:18 -0800, Steve Longerbeam wrote: > There is a block of code in rvin_group_link_notify() that loops through > all entities in the media graph, and prevents enabling a link to a VIN > node if any entity is in use. This prevents enabling a VIN link even if > there is an in-use entity somewhere in the graph that is independent of > the link's pipeline. > > For example, the code will prevent enabling a link from the first > rcar-csi2 receiver to a VIN node even if there is an enabled link > somewhere far upstream on the second independent rcar-csi2 receiver > pipeline. > > If this code is meant to prevent modifying a link if any entity in the > graph is actively involved in streaming (because modifying the CHSEL > register fields can disrupt any/all running streams), then the entities > stream counts should be checked rather than the use counts. > > (There is already such a check in __media_entity_setup_link() that verifies > the stream_count of the link's source and sink entities are both zero, > but that is insufficient, since there should be no running streams in > the entire graph). > > Modify the media_device_for_each_entity() loop to check the entity > stream_count instead of the use_count, and elaborate on the comment. > VIN node links can now be enabled even if there are other independent > in-use entities that are not streaming. > > Fixes: c0cc5aef31 ("media: rcar-vin: add link notify for Gen3") > > Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> > --- > Changes in v2: > - bring back the media_device_for_each_entity() loop but check the > stream_count not the use_count. > --- > drivers/media/platform/rcar-vin/rcar-core.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c > index f0719ce24b97..6dd6b11c1b2b 100644 > --- a/drivers/media/platform/rcar-vin/rcar-core.c > +++ b/drivers/media/platform/rcar-vin/rcar-core.c > @@ -131,9 +131,13 @@ static int rvin_group_link_notify(struct media_link *link, u32 flags, > !is_media_entity_v4l2_video_device(link->sink->entity)) > return 0; > > - /* If any entity is in use don't allow link changes. */ > + /* > + * Don't allow link changes if any entity in the graph is > + * streaming, because modifying the CHSEL register fields > + * can disrupt running streams. > + */ > media_device_for_each_entity(entity, &group->mdev) > - if (entity->use_count) > + if (entity->stream_count) > return -EBUSY; > > mutex_lock(&group->lock); > -- > 2.17.1 >
On 1/9/19 2:40 PM, Niklas Söderlund wrote: > Hi Steve, > > Thanks for your patch, I think it looks good. Thanks for the Ack! I'm not real familiar with the RFC patch process. Should this be submitted again with RFC stripped from the subject line? Steve > On 2019-01-06 13:20:18 -0800, Steve Longerbeam wrote: >> There is a block of code in rvin_group_link_notify() that loops through >> all entities in the media graph, and prevents enabling a link to a VIN >> node if any entity is in use. This prevents enabling a VIN link even if >> there is an in-use entity somewhere in the graph that is independent of >> the link's pipeline. >> >> For example, the code will prevent enabling a link from the first >> rcar-csi2 receiver to a VIN node even if there is an enabled link >> somewhere far upstream on the second independent rcar-csi2 receiver >> pipeline. >> >> If this code is meant to prevent modifying a link if any entity in the >> graph is actively involved in streaming (because modifying the CHSEL >> register fields can disrupt any/all running streams), then the entities >> stream counts should be checked rather than the use counts. >> >> (There is already such a check in __media_entity_setup_link() that verifies >> the stream_count of the link's source and sink entities are both zero, >> but that is insufficient, since there should be no running streams in >> the entire graph). >> >> Modify the media_device_for_each_entity() loop to check the entity >> stream_count instead of the use_count, and elaborate on the comment. >> VIN node links can now be enabled even if there are other independent >> in-use entities that are not streaming. >> >> Fixes: c0cc5aef31 ("media: rcar-vin: add link notify for Gen3") >> >> Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com> > Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> > >> --- >> Changes in v2: >> - bring back the media_device_for_each_entity() loop but check the >> stream_count not the use_count. >> --- >> drivers/media/platform/rcar-vin/rcar-core.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c >> index f0719ce24b97..6dd6b11c1b2b 100644 >> --- a/drivers/media/platform/rcar-vin/rcar-core.c >> +++ b/drivers/media/platform/rcar-vin/rcar-core.c >> @@ -131,9 +131,13 @@ static int rvin_group_link_notify(struct media_link *link, u32 flags, >> !is_media_entity_v4l2_video_device(link->sink->entity)) >> return 0; >> >> - /* If any entity is in use don't allow link changes. */ >> + /* >> + * Don't allow link changes if any entity in the graph is >> + * streaming, because modifying the CHSEL register fields >> + * can disrupt running streams. >> + */ >> media_device_for_each_entity(entity, &group->mdev) >> - if (entity->use_count) >> + if (entity->stream_count) >> return -EBUSY; >> >> mutex_lock(&group->lock); >> -- >> 2.17.1 >>
On 1/9/19 5:19 PM, Steve Longerbeam wrote: > > > On 1/9/19 2:40 PM, Niklas Söderlund wrote: >> Hi Steve, >> >> Thanks for your patch, I think it looks good. > > Thanks for the Ack! I'm not real familiar with the RFC patch process. > Should this be submitted again with RFC stripped from the subject line? I've been told there isn't really a process for RFC patch submission. I will re-submit and strip off the RFC and add your Reviewed-by. Steve > > >> On 2019-01-06 13:20:18 -0800, Steve Longerbeam wrote: >>> There is a block of code in rvin_group_link_notify() that loops through >>> all entities in the media graph, and prevents enabling a link to a VIN >>> node if any entity is in use. This prevents enabling a VIN link even if >>> there is an in-use entity somewhere in the graph that is independent of >>> the link's pipeline. >>> >>> For example, the code will prevent enabling a link from the first >>> rcar-csi2 receiver to a VIN node even if there is an enabled link >>> somewhere far upstream on the second independent rcar-csi2 receiver >>> pipeline. >>> >>> If this code is meant to prevent modifying a link if any entity in the >>> graph is actively involved in streaming (because modifying the CHSEL >>> register fields can disrupt any/all running streams), then the entities >>> stream counts should be checked rather than the use counts. >>> >>> (There is already such a check in __media_entity_setup_link() that >>> verifies >>> the stream_count of the link's source and sink entities are both zero, >>> but that is insufficient, since there should be no running streams in >>> the entire graph). >>> >>> Modify the media_device_for_each_entity() loop to check the entity >>> stream_count instead of the use_count, and elaborate on the comment. >>> VIN node links can now be enabled even if there are other independent >>> in-use entities that are not streaming. >>> >>> Fixes: c0cc5aef31 ("media: rcar-vin: add link notify for Gen3") >>> >>> Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com> >> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se> >> >>> --- >>> Changes in v2: >>> - bring back the media_device_for_each_entity() loop but check the >>> stream_count not the use_count. >>> --- >>> drivers/media/platform/rcar-vin/rcar-core.c | 8 ++++++-- >>> 1 file changed, 6 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/media/platform/rcar-vin/rcar-core.c >>> b/drivers/media/platform/rcar-vin/rcar-core.c >>> index f0719ce24b97..6dd6b11c1b2b 100644 >>> --- a/drivers/media/platform/rcar-vin/rcar-core.c >>> +++ b/drivers/media/platform/rcar-vin/rcar-core.c >>> @@ -131,9 +131,13 @@ static int rvin_group_link_notify(struct >>> media_link *link, u32 flags, >>> !is_media_entity_v4l2_video_device(link->sink->entity)) >>> return 0; >>> - /* If any entity is in use don't allow link changes. */ >>> + /* >>> + * Don't allow link changes if any entity in the graph is >>> + * streaming, because modifying the CHSEL register fields >>> + * can disrupt running streams. >>> + */ >>> media_device_for_each_entity(entity, &group->mdev) >>> - if (entity->use_count) >>> + if (entity->stream_count) >>> return -EBUSY; >>> mutex_lock(&group->lock); >>> -- >>> 2.17.1 >>> >
diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c index f0719ce24b97..6dd6b11c1b2b 100644 --- a/drivers/media/platform/rcar-vin/rcar-core.c +++ b/drivers/media/platform/rcar-vin/rcar-core.c @@ -131,9 +131,13 @@ static int rvin_group_link_notify(struct media_link *link, u32 flags, !is_media_entity_v4l2_video_device(link->sink->entity)) return 0; - /* If any entity is in use don't allow link changes. */ + /* + * Don't allow link changes if any entity in the graph is + * streaming, because modifying the CHSEL register fields + * can disrupt running streams. + */ media_device_for_each_entity(entity, &group->mdev) - if (entity->use_count) + if (entity->stream_count) return -EBUSY; mutex_lock(&group->lock);
There is a block of code in rvin_group_link_notify() that loops through all entities in the media graph, and prevents enabling a link to a VIN node if any entity is in use. This prevents enabling a VIN link even if there is an in-use entity somewhere in the graph that is independent of the link's pipeline. For example, the code will prevent enabling a link from the first rcar-csi2 receiver to a VIN node even if there is an enabled link somewhere far upstream on the second independent rcar-csi2 receiver pipeline. If this code is meant to prevent modifying a link if any entity in the graph is actively involved in streaming (because modifying the CHSEL register fields can disrupt any/all running streams), then the entities stream counts should be checked rather than the use counts. (There is already such a check in __media_entity_setup_link() that verifies the stream_count of the link's source and sink entities are both zero, but that is insufficient, since there should be no running streams in the entire graph). Modify the media_device_for_each_entity() loop to check the entity stream_count instead of the use_count, and elaborate on the comment. VIN node links can now be enabled even if there are other independent in-use entities that are not streaming. Fixes: c0cc5aef31 ("media: rcar-vin: add link notify for Gen3") Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com> --- Changes in v2: - bring back the media_device_for_each_entity() loop but check the stream_count not the use_count. --- drivers/media/platform/rcar-vin/rcar-core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)