[PATCH v3 16/16] drm/amd/display: Trigger modesets on MST DSC connectors

[Francis, David]

I know this looks like it could be a DRM helper, but
 - That would require a DRM-generic way of knowing if a
   connector supports DSC, and current precedent is that
   DSC functionality is stored on a driver-specific basis
 - This function, by necessity, locks global state. Other
   hardware may be able to solve this problem with more fine-
   grained locking, for example by recalculating DSC configs
   and then adding to the state all CRTCs for which the config
   has changed
 - AMD is currently the only user of MST DSC, so if this needs
   to be in DRM, it would be easier to do so once it is
   clear what functionality is common between drivers

________________________________________
From: dri-devel <dri-devel-bounces at lists.freedesktop.org> on behalf of David Francis <David.Francis at amd.com>
Sent: August 21, 2019 4:01 PM
To: dri-devel at lists.freedesktop.org; amd-gfx at lists.freedesktop.org
Cc: Li, Sun peng (Leo); Francis, David; Kazlauskas, Nicholas
Subject: [PATCH v3 16/16] drm/amd/display: Trigger modesets on MST DSC connectors

Whenever a connector on an MST network is attached, detached, or
undergoes a modeset, the DSC configs for each stream on that
topology will be recalculated. This can change their required
bandwidth, requiring a full reprogramming, as though a modeset
was performed, even if that stream did not change timing.

Therefore, whenever a crtc has drm_atomic_crtc_needs_modeset,
for each crtc that shares a MST topology with that stream and
supports DSC, add that crtc (and all affected connectors and
planes) to the atomic state and set mode_changed on its state

v2: Do this check only on Navi and before adding connectors
and planes on modesetting crtcs

Cc: Leo Li <sunpeng.li at amd.com>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
Cc: Lyude Paul <lyude at redhat.com>
Signed-off-by: David Francis <David.Francis at amd.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 77 +++++++++++++++++++
 1 file changed, 77 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 145fd73025dc..702fb0e29053 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6475,7 +6475,73 @@ static int do_aquire_global_lock(struct drm_device *dev,

        return ret < 0 ? ret : 0;
 }
+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
+/*
+ * TODO: This logic should at some point be moved into DRM
+ */
+static int add_affected_mst_dsc_crtcs(struct drm_atomic_state *state, struct drm_crtc *crtc)
+{
+       struct drm_connector *connector;
+       struct drm_connector_state *conn_state;
+       struct drm_connector_list_iter conn_iter;
+       struct drm_crtc_state *new_crtc_state;
+       struct amdgpu_dm_connector *aconnector = NULL, *aconnector_to_add;
+       int i, j;
+       struct drm_crtc *crtcs_affected[AMDGPU_MAX_CRTCS] = { 0 };
+
+       for_each_new_connector_in_state(state, connector, conn_state, i) {
+               if (conn_state->crtc != crtc)
+                       continue;
+
+               aconnector = to_amdgpu_dm_connector(connector);
+               if (!aconnector->port)
+                       aconnector = NULL;
+               else
+                       break;
+       }
+
+       if (!aconnector)
+               return 0;
+
+       i = 0;
+       drm_connector_list_iter_begin(state->dev, &conn_iter);
+       drm_for_each_connector_iter(connector, &conn_iter) {
+               if (!connector->state || !connector->state->crtc)
+                       continue;
+
+               aconnector_to_add = to_amdgpu_dm_connector(connector);
+               if (!aconnector_to_add->port)
+                       continue;
+
+               if (aconnector_to_add->port->mgr != aconnector->port->mgr)
+                       continue;
+
+               if (!aconnector_to_add->dc_sink)
+                       continue;
+
+               if (!aconnector_to_add->dc_sink->sink_dsc_caps.dsc_dec_caps.is_dsc_supported)
+                       continue;
+
+               if (i >= AMDGPU_MAX_CRTCS)
+                       continue;
+
+               crtcs_affected[i] = connector->state->crtc;
+               i++;
+       }
+       drm_connector_list_iter_end(&conn_iter);
+
+       for (j = 0; j < i; j++) {
+               new_crtc_state = drm_atomic_get_crtc_state(state, crtcs_affected[j]);
+               if (IS_ERR(new_crtc_state))
+                       return PTR_ERR(new_crtc_state);

+               new_crtc_state->mode_changed = true;
+       }
+
+       return 0;
+
+}
+#endif
 static void get_freesync_config_for_crtc(
        struct dm_crtc_state *new_crtc_state,
        struct dm_connector_state *new_con_state)
@@ -7160,6 +7226,17 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
        if (ret)
                goto fail;

+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
+       if (adev->asic_type >= CHIP_NAVI10) {
+               for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
+                       if (drm_atomic_crtc_needs_modeset(new_crtc_state)) {
+                               ret = add_affected_mst_dsc_crtcs(state, crtc);
+                               if (ret)
+                                       goto fail;
+                       }
+               }
+       }
+#endif
        for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
                if (!drm_atomic_crtc_needs_modeset(new_crtc_state) &&
                    !new_crtc_state->color_mgmt_changed &&
--
2.17.1

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