linux-kernel - [PATCH 2/3] drm/tegra: Deliver syncpoint base to user space

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Date:	Wed, 9 Oct 2013 14:54:09 +0300
From:	Arto Merilainen <amerilainen@...dia.com>
To:	<tbergstrom@...dia.com>, <thierry.reding@...il.com>
CC:	<dri-devel@...ts.freedesktop.org>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <amerilainen@...dia.com>
Subject: [PATCH 2/3] drm/tegra: Deliver syncpoint base to user space

This patch makes the necessary additions to deliver syncpoint base
to the user space.

This patch splits the index field in the drm_tegra_get_syncpt structure
into three separate fields (index, support_base, base_id). This allows
to keep compatibility over kernel versions:
- The placing of index field stays constant and therefore the interface
  should stay compatible with earlier userspace versions.
- The old index field was input-only and it was not supposed to be read
  afterwards. Delivering data back in the same field should not introduce
  regressions to any old user space applications.
- Old kernels left support_base and base_id fields intact (zero) and
  hence the new user space applications get the correct response from
  the kernel (=syncpoint does not have a base).

Signed-off-by: Arto Merilainen <amerilainen@...dia.com>
---
 drivers/gpu/host1x/drm/drm.c | 2 ++
 include/uapi/drm/tegra_drm.h | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/host1x/drm/drm.c b/drivers/gpu/host1x/drm/drm.c
index 8c61cee..4251563 100644
--- a/drivers/gpu/host1x/drm/drm.c
+++ b/drivers/gpu/host1x/drm/drm.c
@@ -468,6 +468,8 @@ static int tegra_get_syncpt(struct drm_device *drm, void *data,
 
 	syncpt = context->client->syncpts[args->index];
 	args->id = host1x_syncpt_id(syncpt);
+	args->support_base = syncpt->base ? 1 : 0;
+	args->base_id = syncpt->base ? syncpt->base->id : 0;
 
 	return 0;
 }
diff --git a/include/uapi/drm/tegra_drm.h b/include/uapi/drm/tegra_drm.h
index 73bde4e..7a79ca5 100644
--- a/include/uapi/drm/tegra_drm.h
+++ b/include/uapi/drm/tegra_drm.h
@@ -61,7 +61,9 @@ struct drm_tegra_close_channel {
 
 struct drm_tegra_get_syncpt {
 	__u64 context;
-	__u32 index;
+	__u16 index;
+	__u8 support_base;
+	__u8 base_id;
 	__u32 id;
 };
 
-- 
1.8.1.5

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