Re: [RFCv1 11/12] drm: Atomic modeset ioctl

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Oct 07, 2013 at 09:55:47AM -0400, Rob Clark wrote:
> On Mon, Oct 7, 2013 at 9:28 AM, Ville Syrjälä
> <ville.syrjala@linux.intel.com> wrote:
> > On Sat, Oct 05, 2013 at 08:45:49PM -0400, Rob Clark wrote:
> >> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >>
> >> The atomic modeset ioctl cna be used to push any number of new values
> >> for object properties. The driver can then check the full device
> >> configuration as single unit, and try to apply the changes atomically.
> >>
> >> The ioctl simply takes a list of object IDs and property IDs and their
> >> values. For setting values to blob properties, the property value
> >> indicates the length of the data, and the actual data is passed via
> >> another blob pointer.
> >>
> >> The caller can demand non-blocking operation from the ioctl, and if the
> >> driver can't satisfy that requirement an error will be returned.
> >>
> >> The caller can also request to receive asynchronous completion events
> >> after the operation has reached the hardware. An event is sent for each
> >> object specified by the caller, whether or not the actual state of
> >> that object changed. Each event also carries a framebuffer ID, which
> >> indicates to user space that the specified object is no longer
> >> accessing that framebuffer.
> >>
> >> TODO: detailed error reporting?
> >>
> >> v1: original
> >> v2: rebase on uapi changes, and drm state structs.. -- Rob Clark
> >> v3: rebase, missing padding in drm_event_atomic.. -- Rob Clark
> >>
> >> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> ---
> >>  drivers/gpu/drm/drm_crtc.c  | 159 ++++++++++++++++++++++++++++++++++++++++++++
> >>  drivers/gpu/drm/drm_drv.c   |   1 +
> >>  include/drm/drmP.h          |   6 ++
> >>  include/drm/drm_crtc.h      |   2 +
> >>  include/uapi/drm/drm.h      |  12 ++++
> >>  include/uapi/drm/drm_mode.h |  16 +++++
> >>  6 files changed, 196 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> >> index 09396a9..910e5c6 100644
> >> --- a/drivers/gpu/drm/drm_crtc.c
> >> +++ b/drivers/gpu/drm/drm_crtc.c
> >> @@ -4338,3 +4338,162 @@ void drm_mode_config_cleanup(struct drm_device *dev)
> >>       idr_destroy(&dev->mode_config.crtc_idr);
> >>  }
> >>  EXPORT_SYMBOL(drm_mode_config_cleanup);
> >> +
> >> +int drm_mode_atomic_ioctl(struct drm_device *dev,
> >> +                       void *data, struct drm_file *file_priv)
> >> +{
> >> +     struct drm_mode_atomic *arg = data;
> >> +     uint32_t __user *objs_ptr = (uint32_t __user *)(unsigned long)(arg->objs_ptr);
> >> +     uint32_t __user *count_props_ptr = (uint32_t __user *)(unsigned long)(arg->count_props_ptr);
> >> +     uint32_t __user *props_ptr = (uint32_t __user *)(unsigned long)(arg->props_ptr);
> >> +     uint64_t __user *prop_values_ptr = (uint64_t __user *)(unsigned long)(arg->prop_values_ptr);
> >> +     uint64_t __user *blob_values_ptr = (uint64_t __user *)(unsigned long)(arg->blob_values_ptr);
> >> +     unsigned int copied_objs = 0;
> >> +     unsigned int copied_props = 0;
> >> +     unsigned int copied_blobs = 0;
> >> +     void *state;
> >> +     int ret = 0;
> >> +     unsigned int i, j;
> >> +
> >> +     if (arg->flags & ~(DRM_MODE_ATOMIC_TEST_ONLY |
> >> +                     DRM_MODE_ATOMIC_EVENT | DRM_MODE_ATOMIC_NONBLOCK))
> >> +             return -EINVAL;
> >> +
> >> +     /* can't test and expect an event at the same time. */
> >> +     if ((arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) &&
> >> +                     (arg->flags & DRM_MODE_ATOMIC_EVENT))
> >> +             return -EINVAL;
> >> +
> >> +     mutex_lock(&dev->mode_config.mutex);
> >
> > I'm pretty sure I had a version w/ fixed locking...
> >
> > git://gitorious.org/vsyrjala/linux.git rebased_drm_atomic_24
> 
> oh, hmm.. actually the locking should no longer be in the ioctl fxn,
> but should be pushed down to the commit.  looks like I missed this.  I
> need to dig up some actual test code for atomic ioctl ;-)

It can't be in commit. At the very least it has to be around
check+commit, and also you need to hold some locks when you're copying
the current config over to your temp storage. That's assuming you store
_everything_ in the temp storage and so it doesn't matter if the current
state can change between the copy and check+commit.

> 
> >> +
> >> +     state = dev->driver->atomic_begin(dev, arg->flags);
> >> +     if (IS_ERR(state)) {
> >> +             ret = PTR_ERR(state);
> >> +             goto unlock;
> >> +     }
> >> +
> >> +     for (i = 0; i < arg->count_objs; i++) {
> >> +             uint32_t obj_id, count_props;
> >> +             struct drm_mode_object *obj;
> >> +
> >> +             if (get_user(obj_id, objs_ptr + copied_objs)) {
> >> +                     ret = -EFAULT;
> >> +                     goto out;
> >> +             }
> >> +
> >> +             obj = drm_mode_object_find(dev, obj_id, DRM_MODE_OBJECT_ANY);
> >> +             if (!obj || !obj->properties) {
> >> +                     ret = -ENOENT;
> >> +                     goto out;
> >> +             }
> >> +
> >> +             if (arg->flags & DRM_MODE_ATOMIC_EVENT) {
> >> +                     // XXX create atomic event instead..
> >
> > Some people are apparently more comfortable with a per-crtc event
> > rather than the per-obj events I added. So I think we might want
> > both in the end.
> 
> yeah, sorting out events is a bit 'TODO' at the moment.  I do kind of
> like per-crtc event.. it seems easier to implement and I'm not really
> sure what finer event granularity buys us.

Mainly it gets you the old fb. If you limit youself to < vrefresh it's
not a big deal, but going faster than that and you start to want that
information.

> 
> BR,
> -R
> 
 >> +                     struct drm_pending_vblank_event *e =
> >> +                             create_vblank_event(dev, file_priv, arg->user_data);
> >> +                     if (!e) {
> >> +                             ret = -ENOMEM;
> >> +                             goto out;
> >> +                     }
> >> +                     ret = dev->driver->atomic_set_event(dev, state, obj, e);
> >> +                     if (ret) {
> >> +                             destroy_vblank_event(dev, file_priv, e);
> >> +                             goto out;
> >> +                     }
> >> +             }
> >> +
> >> +             if (get_user(count_props, count_props_ptr + copied_objs)) {
> >> +                     ret = -EFAULT;
> >> +                     goto out;
> >> +             }
> >> +
> >> +             copied_objs++;
> >> +
> >> +             for (j = 0; j < count_props; j++) {
> >> +                     uint32_t prop_id;
> >> +                     uint64_t prop_value;
> >> +                     struct drm_mode_object *prop_obj;
> >> +                     struct drm_property *prop;
> >> +                     void *blob_data = NULL;
> >> +
> >> +                     if (get_user(prop_id, props_ptr + copied_props)) {
> >> +                             ret = -EFAULT;
> >> +                             goto out;
> >> +                     }
> >> +
> >> +                     if (!object_has_prop(obj, prop_id)) {
> >> +                             ret = -EINVAL;
> >> +                             goto out;
> >> +                     }
> >> +
> >> +                     prop_obj = drm_mode_object_find(dev, prop_id,
> >> +                                     DRM_MODE_OBJECT_PROPERTY);
> >> +                     if (!prop_obj) {
> >> +                             ret = -ENOENT;
> >> +                             goto out;
> >> +                     }
> >> +                     prop = obj_to_property(prop_obj);
> >> +
> >> +                     if (get_user(prop_value, prop_values_ptr + copied_props)) {
> >> +                             ret = -EFAULT;
> >> +                             goto out;
> >> +                     }
> >> +
> >> +                     if (!drm_property_change_is_valid(prop, prop_value)) {
> >> +                             ret = -EINVAL;
> >> +                             goto out;
> >> +                     }
> >> +
> >> +                     if ((prop->flags & DRM_MODE_PROP_BLOB) && prop_value) {
> >> +                             uint64_t blob_ptr;
> >> +
> >> +                             if (get_user(blob_ptr, blob_values_ptr + copied_blobs)) {
> >> +                                     ret = -EFAULT;
> >> +                                     goto out;
> >> +                             }
> >> +
> >> +                             blob_data = kmalloc(prop_value, GFP_KERNEL);
> >> +                             if (!blob_data) {
> >> +                                     ret = -ENOMEM;
> >> +                                     goto out;
> >> +                             }
> >> +
> >> +                             if (copy_from_user(blob_data, (void __user *)(unsigned long)blob_ptr, prop_value)) {
> >> +                                     kfree(blob_data);
> >> +                                     ret = -EFAULT;
> >> +                                     goto out;
> >> +                             }
> >> +                     }
> >> +
> >> +                     /* User space sends the blob pointer even if we
> >> +                      * don't use it (length==0).
> >> +                      */
> >> +                     if (prop->flags & DRM_MODE_PROP_BLOB)
> >> +                             copied_blobs++;
> >> +
> >> +                     /* The driver will be in charge of blob_data from now on. */
> >> +                     ret = drm_mode_set_obj_prop(obj, state, prop,
> >> +                                     prop_value, blob_data);
> >> +                     if (ret)
> >> +                             goto out;
> >> +
> >> +                     copied_props++;
> >> +             }
> >> +     }
> >> +
> >> +     ret = dev->driver->atomic_check(dev, state);
> >> +     if (ret)
> >> +             goto out;
> >> +
> >> +     if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY)
> >> +             goto out;
> >> +
> >> +     ret = dev->driver->atomic_commit(dev, state);
> >> +
> >> + out:
> >> +     dev->driver->atomic_end(dev, state);
> >> + unlock:
> >> +     mutex_unlock(&dev->mode_config.mutex);
> >> +
> >> +     return ret;
> >> +}
> >> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> >> index e572dd2..43e04ae 100644
> >> --- a/drivers/gpu/drm/drm_drv.c
> >> +++ b/drivers/gpu/drm/drm_drv.c
> >> @@ -166,6 +166,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
> >>       DRM_IOCTL_DEF(DRM_IOCTL_MODE_OBJ_GETPROPERTIES, drm_mode_obj_get_properties_ioctl, DRM_CONTROL_ALLOW|DRM_UNLOCKED),
> >>       DRM_IOCTL_DEF(DRM_IOCTL_MODE_OBJ_SETPROPERTY, drm_mode_obj_set_property_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
> >>       DRM_IOCTL_DEF(DRM_IOCTL_MODE_CURSOR2, drm_mode_cursor2_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
> >> +     DRM_IOCTL_DEF(DRM_IOCTL_MODE_ATOMIC, drm_mode_atomic_ioctl, DRM_MASTER|DRM_CONTROL_ALLOW|DRM_UNLOCKED),
> >>  };
> >>
> >>  #define DRM_CORE_IOCTL_COUNT ARRAY_SIZE( drm_ioctls )
> >> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> >> index 4c3de22..f282733 100644
> >> --- a/include/drm/drmP.h
> >> +++ b/include/drm/drmP.h
> >> @@ -1158,6 +1158,12 @@ struct drm_pending_vblank_event {
> >>       struct drm_event_vblank event;
> >>  };
> >>
> >> +struct drm_pending_atomic_event {
> >> +     struct drm_pending_event base;
> >> +     int pipe;
> >> +     struct drm_event_atomic event;
> >> +};
> >> +
> >>  /**
> >>   * DRM device structure. This structure represent a complete card that
> >>   * may contain multiple heads.
> >> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> >> index 86a5a00..fa3956e 100644
> >> --- a/include/drm/drm_crtc.h
> >> +++ b/include/drm/drm_crtc.h
> >> @@ -1313,6 +1313,8 @@ extern int drm_mode_obj_get_properties_ioctl(struct drm_device *dev, void *data,
> >>                                            struct drm_file *file_priv);
> >>  extern int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data,
> >>                                          struct drm_file *file_priv);
> >> +extern int drm_mode_atomic_ioctl(struct drm_device *dev,
> >> +                              void *data, struct drm_file *file_priv);
> >>
> >>  extern void drm_fb_get_bpp_depth(uint32_t format, unsigned int *depth,
> >>                                int *bpp);
> >> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> >> index ece8678..efb1461 100644
> >> --- a/include/uapi/drm/drm.h
> >> +++ b/include/uapi/drm/drm.h
> >> @@ -733,6 +733,7 @@ struct drm_prime_handle {
> >>  #define DRM_IOCTL_MODE_OBJ_GETPROPERTIES     DRM_IOWR(0xB9, struct drm_mode_obj_get_properties)
> >>  #define DRM_IOCTL_MODE_OBJ_SETPROPERTY       DRM_IOWR(0xBA, struct drm_mode_obj_set_property)
> >>  #define DRM_IOCTL_MODE_CURSOR2               DRM_IOWR(0xBB, struct drm_mode_cursor2)
> >> +#define DRM_IOCTL_MODE_ATOMIC                DRM_IOWR(0xBC, struct drm_mode_atomic)
> >>
> >>  /**
> >>   * Device specific ioctls should only be in their respective headers
> >> @@ -774,6 +775,17 @@ struct drm_event_vblank {
> >>       __u32 reserved;
> >>  };
> >>
> >> +struct drm_event_atomic {
> >> +     struct drm_event base;
> >> +     __u64 user_data;
> >> +     __u32 tv_sec;
> >> +     __u32 tv_usec;
> >> +     __u32 sequence;
> >> +     __u32 obj_id;
> >> +     __u32 old_fb_id;
> >> +     __u32 reserved;
> >> +};
> >> +
> >>  #define DRM_CAP_DUMB_BUFFER 0x1
> >>  #define DRM_CAP_VBLANK_HIGH_CRTC 0x2
> >>  #define DRM_CAP_DUMB_PREFERRED_DEPTH 0x3
> >> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> >> index 6d4f089..03a473c 100644
> >> --- a/include/uapi/drm/drm_mode.h
> >> +++ b/include/uapi/drm/drm_mode.h
> >> @@ -489,4 +489,20 @@ struct drm_mode_destroy_dumb {
> >>       uint32_t handle;
> >>  };
> >>
> >> +#define DRM_MODE_ATOMIC_TEST_ONLY (1<<0)
> >> +#define DRM_MODE_ATOMIC_EVENT (1<<1)
> >> +#define DRM_MODE_ATOMIC_NONBLOCK (1<<2)
> >> +
> >> +/* FIXME come up with some sane error reporting mechanism? */
> >> +struct drm_mode_atomic {
> >> +     __u32 flags;
> >> +     __u32 count_objs;
> >> +     __u64 objs_ptr;
> >> +     __u64 count_props_ptr;
> >> +     __u64 props_ptr;
> >> +     __u64 prop_values_ptr;
> >> +     __u64 blob_values_ptr;
> >> +     __u64 user_data;
> >> +};
> >> +
> >>  #endif
> >> --
> >> 1.8.3.1
> >
> > --
> > Ville Syrjälä
> > Intel OTC

-- 
Ville Syrjälä
Intel OTC