On Tue, Jan 03, 2017 at 01:01:49PM -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 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>
Overall issue with the patch is that dp helpers now have 2 places where
available_slots is stored: One for atomic drivers in ->state, and the
legacy one. I think it'd be good to rework the legacy codepaths (i.e.
drm_dp_find_vcpi_slots) to use mgr->state->avail_slots, and remove
mgr->avail_slots entirely.
Another design concern below, but in principle this looks like what we
need.
-Daniel
> ---
> drivers/gpu/drm/drm_atomic.c | 66 +++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/drm_atomic_helper.c | 10 ++++++
> drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++
> include/drm/drm_atomic.h | 13 +++++++
> include/drm/drm_dp_mst_helper.h | 13 +++++++
> 5 files changed, 112 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 681d5f9..b8e2cea 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -31,6 +31,7 @@
> #include <drm/drm_mode.h>
> #include <drm/drm_plane_helper.h>
> #include <drm/drm_print.h>
> +#include <drm/drm_dp_mst_helper.h>
> #include <linux/sync_file.h>
>
> #include "drm_crtc_internal.h"
> @@ -62,6 +63,7 @@ void drm_atomic_state_default_release(struct drm_atomic_state *state)
> kfree(state->connectors);
> kfree(state->crtcs);
> kfree(state->planes);
> + kfree(state->dp_mst_topologies);
> }
> EXPORT_SYMBOL(drm_atomic_state_default_release);
>
> @@ -189,6 +191,18 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
> state->planes[i].ptr = NULL;
> state->planes[i].state = NULL;
> }
> +
> + for (i = 0; i < state->num_mst_topologies; i++) {
> + struct drm_dp_mst_topology_mgr *mgr = state->dp_mst_topologies[i].ptr;
> +
> + if (!mgr)
> + continue;
> +
> + kfree(state->dp_mst_topologies[i].state);
> + state->dp_mst_topologies[i].ptr = NULL;
> + state->dp_mst_topologies[i].state = NULL;
> + }
> +
> }
> EXPORT_SYMBOL(drm_atomic_state_default_clear);
>
> @@ -981,6 +995,58 @@ static void drm_atomic_plane_print_state(struct drm_printer *p,
> plane->funcs->atomic_print_state(p, state);
> }
>
> +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 ret, i;
> + size_t new_size;
> + struct __drm_dp_mst_topology_state *new_arr;
> + struct drm_dp_mst_topology_state *new_mst_state;
> + int num_topologies;
> + struct drm_mode_config *config = &mgr->dev->mode_config;
> +
> + WARN_ON(!state->acquire_ctx);
> +
> + ret = drm_modeset_lock(&config->connection_mutex, state->acquire_ctx);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + for (i = 0; i < state->num_mst_topologies; i++) {
> + if (mgr == state->dp_mst_topologies[i].ptr &&
> + state->dp_mst_topologies[i].state) {
> + return state->dp_mst_topologies[i].state;
> + }
> + }
> +
> + num_topologies = state->num_mst_topologies + 1;
> + new_size = sizeof(*state->dp_mst_topologies) * num_topologies;
> + new_arr = krealloc(state->dp_mst_topologies, new_size, GFP_KERNEL);
> + if (!new_arr)
> + return ERR_PTR(-ENOMEM);
> +
> + state->dp_mst_topologies = new_arr;
> + memset(&state->dp_mst_topologies[state->num_mst_topologies], 0,
> + sizeof(*state->dp_mst_topologies));
> +
> + new_mst_state = kmalloc(sizeof(*mgr->state), GFP_KERNEL);
> + if (!new_mst_state)
> + return ERR_PTR(-ENOMEM);
> +
> + new_mst_state->avail_slots = mgr->state->avail_slots;
> + state->dp_mst_topologies[state->num_mst_topologies].state = new_mst_state;
> + state->dp_mst_topologies[state->num_mst_topologies].ptr = mgr;
> + state->num_mst_topologies = num_topologies;
> + new_mst_state->mgr = mgr;
> + mgr->state->state = state;
> +
> + DRM_DEBUG_ATOMIC("Added [MST Topology w/ base connector:%d] %p state to %p\n",
> + mgr->conn_base_id, new_mst_state, state);
> +
> + return new_mst_state;
> +}
> +EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
> +
> /**
> * drm_atomic_get_connector_state - get connector state
> * @state: global atomic state object
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 5e52244..1cd38b7 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -30,6 +30,7 @@
> #include <drm/drm_plane_helper.h>
> #include <drm/drm_crtc_helper.h>
> #include <drm/drm_atomic_helper.h>
> +#include <drm/drm_dp_mst_helper.h>
> #include <linux/dma-fence.h>
>
> #include "drm_crtc_internal.h"
> @@ -1992,6 +1993,15 @@ void drm_atomic_helper_swap_state(struct drm_atomic_state *state,
> connector->state->state = NULL;
> }
>
> + for (i = 0; i < state->num_mst_topologies; i++) {
> + struct drm_dp_mst_topology_mgr *mgr;
> +
> + mgr = state->dp_mst_topologies[i].ptr;
> + mgr->state->state = state;
> + swap(state->dp_mst_topologies[i].state, mgr->state);
> + mgr->state->state = NULL;
> + }
I'm not sure we want to tie the dp mst helpers that closely with the
atomic machinery, otoh it makes things a lot easier. My concern is that
drm_atomic_state is a core structure, whereas the dp_mst stuff is a
helper, which means we have a control inversion here compared to the
normal pattern.
> +
> for_each_crtc_in_state(state, crtc, crtc_state, i) {
> crtc->state->state = state;
> swap(state->crtcs[i].state, crtc->state);
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index d42a6c0..1be19e1 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2042,6 +2042,9 @@ 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;
> +
> /* add initial branch device at LCT 1 */
> mstb = drm_dp_add_mst_branch_device(1, NULL);
> if (mstb == NULL) {
> @@ -2973,6 +2976,11 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
> mgr->proposed_vcpis = kcalloc(max_payloads, sizeof(struct drm_dp_vcpi *), GFP_KERNEL);
> if (!mgr->proposed_vcpis)
> return -ENOMEM;
> + mgr->state = kzalloc(sizeof(*mgr->state), GFP_KERNEL);
> + if (!mgr->state)
> + return -ENOMEM;
> + mgr->state->mgr = mgr;
> +
> set_bit(0, &mgr->payload_mask);
> if (test_calc_pbn_mode() < 0)
> DRM_ERROR("MST PBN self-test failed\n");
> @@ -2995,6 +3003,8 @@ void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
> kfree(mgr->proposed_vcpis);
> mgr->proposed_vcpis = NULL;
> mutex_unlock(&mgr->payload_lock);
> + kfree(mgr->state);
> + mgr->state = NULL;
> mgr->dev = NULL;
> mgr->aux = NULL;
> }
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index fd2d971..7ac5ed6 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -153,6 +153,11 @@ struct __drm_connnectors_state {
> struct drm_connector_state *state;
> };
>
> +struct __drm_dp_mst_topology_state {
> + struct drm_dp_mst_topology_mgr *ptr;
> + struct drm_dp_mst_topology_state *state;
One way to fix that control inversion I mentioned above is to use void*
pionters here, and then have callbacks for atomic_destroy and swap_state
on top. A bit more shuffling, but we could then use that for other driver
private objects.
Other option is to stuff it into intel_atomic_state.
> +};
> +
> /**
> * struct drm_atomic_state - the global state object for atomic updates
> * @ref: count of all references to this state (will not be freed until zero)
> @@ -164,6 +169,8 @@ struct __drm_connnectors_state {
> * @crtcs: pointer to array of CRTC pointers
> * @num_connector: size of the @connectors and @connector_states arrays
> * @connectors: pointer to array of structures with per-connector data
> + * @num_mst_topologies: size of the @dp_mst_topologies array
> + * @dp_mst_topologies: pointer to array of structures with per-MST topology manager data
> * @acquire_ctx: acquire context for this atomic modeset state update
> */
> struct drm_atomic_state {
> @@ -177,6 +184,8 @@ struct drm_atomic_state {
> struct __drm_crtcs_state *crtcs;
> int num_connector;
> struct __drm_connnectors_state *connectors;
> + int num_mst_topologies;
> + struct __drm_dp_mst_topology_state *dp_mst_topologies;
>
> struct drm_modeset_acquire_ctx *acquire_ctx;
>
> @@ -250,6 +259,10 @@ int drm_atomic_connector_set_property(struct drm_connector *connector,
> struct drm_connector_state *state, struct drm_property *property,
> uint64_t val);
>
> +struct drm_dp_mst_topology_state * __must_check
> +drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
> + struct drm_dp_mst_topology_mgr *mgr);
> +
> /**
> * drm_atomic_get_existing_crtc_state - get crtc state, if it exists
> * @state: global atomic state object
> diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
> index 98d3c73..0a9bf20 100644
> --- a/include/drm/drm_dp_mst_helper.h
> +++ b/include/drm/drm_dp_mst_helper.h
> @@ -403,6 +403,12 @@ 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 +487,11 @@ struct drm_dp_mst_topology_mgr {
> int pbn_div;
>
> /**
> + * @state: MST topology manager state for atomic modesetting drivers
> + */
> + struct drm_dp_mst_topology_state *state;
> +
> + /**
> * @qlock: protects @tx_msg_downq, the tx_slots in struct
> * &drm_dp_mst_branch and txmsg->state once they are queued
> */
> @@ -596,4 +607,6 @@ 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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