Re: [PATCH v5 3/4] drm/fence: add fence timeline to drm_crtc

From: Brian Starkey
Date: Thu Oct 20 2016 - 13:21:45 EST


Hi Gustavo,

On Thu, Oct 20, 2016 at 12:50:04PM -0200, Gustavo Padovan wrote:
From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>

Create one timeline context for each CRTC to be able to handle out-fences
and signal them. It adds a few members to struct drm_crtc: fence_context,
where we store the context we get from fence_context_alloc(), the
fence seqno and the fence lock, that we pass in fence_init() to be
used by the fence.

v2: Comment by Daniel Stone:
- add BUG_ON() to fence_to_crtc() macro

v3: Comment by Ville Syrjälä
- Use more meaningful name as crtc timeline name

Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_crtc.c | 31 +++++++++++++++++++++++++++++++
include/drm/drm_crtc.h | 19 +++++++++++++++++++
2 files changed, 50 insertions(+)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index fcb6453..b99090f 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -165,6 +165,32 @@ static void drm_crtc_crc_fini(struct drm_crtc *crtc)
#endif
}

+static const char *drm_crtc_fence_get_driver_name(struct fence *fence)
+{
+ struct drm_crtc *crtc = fence_to_crtc(fence);
+
+ return crtc->dev->driver->name;
+}
+
+static const char *drm_crtc_fence_get_timeline_name(struct fence *fence)
+{
+ struct drm_crtc *crtc = fence_to_crtc(fence);
+
+ return crtc->timeline_name;
+}
+
+static bool drm_crtc_fence_enable_signaling(struct fence *fence)
+{
+ return true;
+}
+
+const struct fence_ops drm_crtc_fence_ops = {
+ .get_driver_name = drm_crtc_fence_get_driver_name,
+ .get_timeline_name = drm_crtc_fence_get_timeline_name,
+ .enable_signaling = drm_crtc_fence_enable_signaling,
+ .wait = fence_default_wait,
+};
+
/**
* drm_crtc_init_with_planes - Initialise a new CRTC object with
* specified primary and cursor planes.
@@ -222,6 +248,11 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
return -ENOMEM;
}

+ crtc->fence_context = fence_context_alloc(1);
+ spin_lock_init(&crtc->fence_lock);
+ snprintf(crtc->timeline_name, sizeof(crtc->timeline_name),
+ "drm_crtc-%d", crtc->base.id);

I wondered about "[CRTC:id:name]" to be consistent with the DRM debug
prints.

+
crtc->base.properties = &crtc->properties;

list_add_tail(&crtc->head, &config->crtc_list);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 279132e..657a33a 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -32,6 +32,8 @@
#include <linux/fb.h>
#include <linux/hdmi.h>
#include <linux/media-bus-format.h>
+#include <linux/srcu.h>
+#include <linux/fence.h>
#include <uapi/drm/drm_mode.h>
#include <uapi/drm/drm_fourcc.h>
#include <drm/drm_modeset_lock.h>
@@ -618,6 +620,9 @@ struct drm_crtc_funcs {
* @gamma_store: gamma ramp values
* @helper_private: mid-layer private data
* @properties: property tracking for this CRTC
+ * @fence_context: context for fence signalling
+ * @fence_lock: fence lock for the fence context
+ * @fence_seqno: seqno variable to create fences

@timeline_name ?

Cheers,
Brian

*
* Each CRTC may have one or more connectors associated with it. This structure
* allows the CRTC to be controlled.
@@ -726,8 +731,22 @@ struct drm_crtc {
*/
struct drm_crtc_crc crc;
#endif
+
+ /* fence timelines info for DRM out-fences */
+ unsigned int fence_context;
+ spinlock_t fence_lock;
+ unsigned long fence_seqno;
+ char timeline_name[32];
};

+extern const struct fence_ops drm_crtc_fence_ops;
+
+static inline struct drm_crtc *fence_to_crtc(struct fence *fence)
+{
+ BUG_ON(fence->ops != &drm_crtc_fence_ops);
+ return container_of(fence->lock, struct drm_crtc, fence_lock);
+}
+
/**
* struct drm_mode_set - new values for a CRTC config change
* @fb: framebuffer to use for new config
--
2.5.5

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