Messages in this thread | | | Subject | Re: [RFC PATCH v2] media: rcar-vin: Allow independent VIN link enablement | From | Steve Longerbeam <> | Date | Mon, 14 Jan 2019 17:03:35 -0800 |
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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 >>> >
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