On Tue, Jan 24, 2017 at 03:49:33PM -0800, Dhinakaran Pandiyan wrote:
> Link bandwidth is shared between multiple display streams in DP MST
> configurations. The DP MST topology manager structure maintains the
> shared link bandwidth for a primary link directly connected to the GPU. For
> atomic modesetting drivers, checking if there is sufficient link bandwidth
> for a mode needs to be done during the atomic_check phase to avoid failed
> modesets. Let's encsapsulate the available link bw information in a
> private state structure so that bw can be allocated and released atomically
> for each of the ports sharing the primary link.
>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
Yeah, I like how this neatly hides all the atomic state tracking now, and
just leaves the mst specific logic in the mst helpers.
> ---
> drivers/gpu/drm/drm_dp_mst_topology.c | 60 +++++++++++++++++++++++++++++++++++
> include/drm/drm_dp_mst_helper.h | 20 ++++++++++++
> 2 files changed, 80 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index b871d4e..247286b 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2042,6 +2042,8 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
> goto out_unlock;
> }
>
> + /* max. time slots - one slot for MTP header */
> + mgr->state->avail_slots = 63;
We can't reset atomic state on each hotplug, that would wreak the atomic
tracking. E.g. there might still be a pipe around running on this output,
and then we'd go above 63 slots when we release that one. You need to init
this once in drm_dp_mst_topology_mgr_init() and then make sure it's always
accurate.
> /* add initial branch device at LCT 1 */
> mstb = drm_dp_add_mst_branch_device(1, NULL);
> if (mstb == NULL) {
> @@ -2935,6 +2937,55 @@ static void drm_dp_destroy_connector_work(struct work_struct *work)
> (*mgr->cbs->hotplug)(mgr);
> }
>
> +void drm_dp_mst_destroy_state(void *obj_state)
> +{
> + kfree(obj_state);
> +}
> +
> +void drm_dp_mst_swap_state(void *obj, void **obj_state_ptr)
> +{
> + struct drm_dp_mst_topology_mgr *mgr = obj;
> + struct drm_dp_mst_topology_state **topology_state_ptr;
> +
> + topology_state_ptr = (struct drm_dp_mst_topology_state **)obj_state_ptr;
> +
> + mgr->state->state = (*topology_state_ptr)->state;
> + swap(*topology_state_ptr, mgr->state);
> + mgr->state->state = NULL;
> +}
> +
> +void *drm_dp_mst_duplicate_state(struct drm_atomic_state *state, void *obj)
> +{
> + struct drm_dp_mst_topology_mgr *mgr = obj;
> + struct drm_dp_mst_topology_state *new_mst_state;
> +
> + if (WARN_ON(!mgr->state))
> + return NULL;
> +
> + new_mst_state = kmalloc(sizeof(*new_mst_state), GFP_KERNEL);
> + if (new_mst_state) {
> + new_mst_state->avail_slots = mgr->state->avail_slots;
> + new_mst_state->mgr = mgr;
> + new_mst_state->state = state;
> + }
kmemdup is less code :-)
> +
> + return new_mst_state;
> +}
> +
> +static const struct drm_private_state_funcs mst_state_funcs = {
> + .swap_state = drm_dp_mst_swap_state,
> + .destroy_state = drm_dp_mst_destroy_state,
> + .duplicate_state = drm_dp_mst_duplicate_state,
> +};
> +
Needs a few lines of kernel-doc here since it's an exported function.
Cheers, Daniel
> +struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
> + struct drm_dp_mst_topology_mgr *mgr)
> +{
> + return drm_atomic_get_priv_obj_state(state, mgr,
> + &mst_state_funcs);
> +}
> +EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
> +
> /**
> * drm_dp_mst_topology_mgr_init - initialise a topology manager
> * @mgr: manager struct to initialise
> @@ -2979,6 +3030,12 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
> if (test_calc_pbn_mode() < 0)
> DRM_ERROR("MST PBN self-test failed\n");
>
> + mgr->state = kzalloc(sizeof(*mgr->state), GFP_KERNEL);
> + if (mgr->state == NULL)
> + return -ENOMEM;
> + mgr->state->mgr = mgr;
> + mgr->funcs = &mst_state_funcs;
> +
> return 0;
> }
> EXPORT_SYMBOL(drm_dp_mst_topology_mgr_init);
> @@ -2999,6 +3056,9 @@ void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
> mutex_unlock(&mgr->payload_lock);
> mgr->dev = NULL;
> mgr->aux = NULL;
> + kfree(mgr->state);
> + mgr->state = NULL;
> + mgr->funcs = NULL;
> }
> EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy);
>
> diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
> index 98d3c73..8cbdbfa 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -24,6 +24,7 @@
>
> #include <linux/types.h>
> #include <drm/drm_dp_helper.h>
> +#include <drm/drm_atomic.h>
>
> struct drm_dp_mst_branch;
>
> @@ -403,6 +404,12 @@ struct drm_dp_payload {
> int vcpi;
> };
>
> +struct drm_dp_mst_topology_state {
> + int avail_slots;
> + struct drm_atomic_state *state;
> + struct drm_dp_mst_topology_mgr *mgr;
> +};
> +
> /**
> * struct drm_dp_mst_topology_mgr - DisplayPort MST manager
> *
> @@ -481,6 +488,16 @@ struct drm_dp_mst_topology_mgr {
> int pbn_div;
>
> /**
> + * @state: State information for topology manager
> + */
> + struct drm_dp_mst_topology_state *state;
> +
> + /**
> + * @funcs: Atomic helper callbacks
> + */
> + const struct drm_private_state_funcs *funcs;
> +
> + /**
> * @qlock: protects @tx_msg_downq, the tx_slots in struct
> * &drm_dp_mst_branch and txmsg->state once they are queued
> */
> @@ -596,4 +613,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>
> 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);
> +
> #endif
> --
> 2.7.4
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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