queue-4.19/media-rcar-vin-allow-independent-vin-link-enablement.patch

   1 From ce5a41d12dd7b451edbfc0345f7cb7932558d615 Mon Sep 17 00:00:00 2001
   2 From: Steve Longerbeam <slongerbeam@gmail.com>
   3 Date: Mon, 14 Jan 2019 20:10:19 -0500
   4 Subject: media: rcar-vin: Allow independent VIN link enablement
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   8
   9 [ Upstream commit c5ff0edb8e2270a75935c73217fb0de1abd2d910 ]
  10
  11 There is a block of code in rvin_group_link_notify() that prevents
  12 enabling a link to a VIN node if any entity in the media graph is
  13 in use. This prevents enabling a VIN link even if there is an in-use
  14 entity somewhere in the graph that is independent of the link's
  15 pipeline.
  16
  17 For example, the code block will prevent enabling a link from
  18 the first rcar-csi2 receiver to a VIN node even if there is an
  19 enabled link somewhere far upstream on the second independent
  20 rcar-csi2 receiver pipeline.
  21
  22 If this code block is meant to prevent modifying a link if any entity
  23 in the graph is actively involved in streaming (because modifying
  24 the CHSEL register fields can disrupt any/all running streams), then
  25 the entities stream counts should be checked rather than the use counts.
  26
  27 (There is already such a check in __media_entity_setup_link() that verifies
  28 the stream_count of the link's source and sink entities are both zero,
  29 but that is insufficient, since there should be no running streams in
  30 the entire graph).
  31
  32 Modify the code block to check the entity stream_count instead of the
  33 use_count (and elaborate on the comment). VIN node links can now be
  34 enabled even if there are other independent in-use entities that are
  35 not streaming.
  36
  37 Fixes: c0cc5aef31 ("media: rcar-vin: add link notify for Gen3")
  38
  39 Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
  40 Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
  41 Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
  42 Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
  43 Signed-off-by: Sasha Levin <sashal@kernel.org>
  44 ---
  45  drivers/media/platform/rcar-vin/rcar-core.c | 8 ++++++--
  46  1 file changed, 6 insertions(+), 2 deletions(-)
  47
  48 diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c
  49 index ce09799976ef..e1085e3ab3cc 100644
  50 --- a/drivers/media/platform/rcar-vin/rcar-core.c
  51 +++ b/drivers/media/platform/rcar-vin/rcar-core.c
  52 @@ -131,9 +131,13 @@ static int rvin_group_link_notify(struct media_link *link, u32 flags,
  53             !is_media_entity_v4l2_video_device(link->sink->entity))
  54                 return 0;
  55
  56 -       /* If any entity is in use don't allow link changes. */
  57 +       /*
  58 +        * Don't allow link changes if any entity in the graph is
  59 +        * streaming, modifying the CHSEL register fields can disrupt
  60 +        * running streams.
  61 +        */
  62         media_device_for_each_entity(entity, &group->mdev)
  63 -               if (entity->use_count)
  64 +               if (entity->stream_count)
  65                         return -EBUSY;
  66
  67         mutex_lock(&group->lock);
  68 --
  69 2.19.1
  70