On Thu, 2017-03-30 at 01:42 -0700, Dhinakaran Pandiyan wrote:
> From: "Pandiyan, Dhinakaran" <dhinakaran.pandiyan@xxxxxxxxx>
>
> drm_dp_atomic_find_vcpi_slots() should be called from ->atomic_check() to
> check there are sufficient vcpi slots for a mode and to add that to the
> state. This should be followed by a call to drm_dp_mst_allocate_vcpi()
> in ->atomic_commit() to initialize a struct vcpi for the port.
>
> drm_dp_atomic_release_vcpi_slots() should be called from
> ->atomic_check() to release a port's vcpi slot allocation from the
> state.
>
> Drivers that do not make use of this atomic helper are expected to call
> drm_dp_find_vcpi_slots() instead before calling
> drm_dp_mst_allocate_vcpi().
>
> v2:
> Added checks for verifying the port reference is valid
> Moved get_mst_topology_state() into the helpers (Daniel)
> Changed find_vcpi_slots() to not depend on current allocation
>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Archit Taneja <architt@xxxxxxxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Harry Wentland <Harry.wentland@xxxxxxx>
> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 75 +++++++++++++++++++++++++++++++++++
> include/drm/drm_dp_mst_helper.h | 6 +++
> 2 files changed, 81 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 0ad0baa..9f3954e 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2498,6 +2498,81 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
> }
>
> /**
> + * drm_dp_atomic_find_vcpi_slots() - Find and add vcpi slots to the state
> + * @state: global atomic state
> + * @mgr: MST topology manager for the port
> + * @port: port to find vcpi slots for
> + * @pbn: bandwidth required for the mode in PBN
> + *
> + * RETURNS:
> + * Total slots in the atomic state assigned for this port or error
> + */
> +int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
> + struct drm_dp_mst_topology_mgr *mgr,
> + struct drm_dp_mst_port *port, int pbn)
> +{
> + struct drm_dp_mst_topology_state *topology_state;
> + int req_slots;
> +
> + topology_state = drm_atomic_get_mst_topology_state(state, mgr);
> + if (topology_state == NULL)
> + return -ENOMEM;
> +
> + port = drm_dp_get_validated_port_ref(mgr, port);
> + if (port == NULL)
> + return -EINVAL;
> + req_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
> + DRM_DEBUG_KMS("vcpi slots req=%d, avail=%d\n",
> + req_slots, topology_state->avail_slots);
> +
> + if (req_slots > topology_state->avail_slots) {
> + drm_dp_put_port(port);
> + return -ENOSPC;
> + }
> +
> + topology_state->avail_slots -= req_slots;
> + DRM_DEBUG_KMS("vcpi slots avail=%d", topology_state->avail_slots);
> +
> + drm_dp_put_port(port);
> + return req_slots;
> +}
> +EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
> +
> +/**
> + * drm_dp_atomic_release_vcpi_slots() - Release allocated vcpi slots
> + * @state: global atomic state
> + * @mgr: MST topology manager for the port
> + * @port: port to release the vcpi slots for
> + *
> + * RETURNS:
> + * Number of slots released from the atomic state for this port
> + */
> +int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
> + struct drm_dp_mst_topology_mgr *mgr,
> + struct drm_dp_mst_port *port)
> +{
> + struct drm_dp_mst_topology_state *topology_state;
> + int curr_slots;
> +
> + topology_state = drm_atomic_get_mst_topology_state(state, mgr);
> + if (topology_state == NULL)
> + return -ENOMEM;
> +
> + port = drm_dp_get_validated_port_ref(mgr, port);
> + if (port == NULL)
> + return -EINVAL;
> +
> + curr_slots = port->vcpi.num_slots;
This is a problem if the port has been destroyed.
> + topology_state->avail_slots += curr_slots;
> + DRM_DEBUG_KMS("vcpi slots released=%d, avail=%d\n",
> + curr_slots, topology_state->avail_slots);
> +
> + drm_dp_put_port(port);
> + return curr_slots;
> +}
Should we do this instead?
int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
struct drm_dp_mst_topology_mgr *mgr,
struct drm_dp_mst_port *port, int
slots)
{
struct drm_dp_mst_topology_state *topology_state;
topology_state = drm_atomic_get_mst_topology_state(state, mgr);
if (topology_state == NULL)
return -ENOMEM;
/* We cannot rely on port->vcpi.num_slots to update
* topology_state->avail_slots as the port may not exist if the
parent
* branch device was unplugged. This should be fixed by tracking
* per-port slot allocation in drm_dp_mst_topology_state instead
of
* depending on the caller to tell us how many slots to release.
*/
topology_state->avail_slots += slots;
DRM_DEBUG_KMS("vcpi slots released=%d, avail=%d\n",
slots, topology_state->avail_slots);
return 0;
}
> +EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);
> +
> +/**
> * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel
> * @mgr: manager for this port
> * @port: port to allocate a virtual channel for.
> diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
> index 0b371df..64e7dac 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -615,5 +615,11 @@ void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr);
> int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr);
> struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
> struct drm_dp_mst_topology_mgr *mgr);
> +int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
> + struct drm_dp_mst_topology_mgr *mgr,
> + struct drm_dp_mst_port *port, int pbn);
> +int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
> + struct drm_dp_mst_topology_mgr *mgr,
> + struct drm_dp_mst_port *port);
>
> #endif
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