Re: [RFC PATCH v2 2/3] drm/bridge: cadence: cdns-mhdp8546*: Change drm_connector from pointer to structure

Tue, 27 May 2025 04:35:59 -0700 



On 27/05/25 14:59, Jayesh Choudhary wrote:

Hello Tomi,

On 27/05/25 13:28, Tomi Valkeinen wrote:

Hi,

On 21/05/2025 10:32, Jayesh Choudhary wrote:

After adding DBANC framework, mhdp->connector is not initialised during

bridge calls. But the asyncronous work scheduled depends on the 
connector.

We cannot get to drm_atomic_state in these asyncronous calls running on
worker threads. So we need to store the data that we need in mhdp bridge
structure.

Like other bridge drivers, use drm_connector pointer instead of 
structure

and make appropriate changes to the conditionals and assignments related
to mhdp->connector.
Also, in the atomic enable call, move the connector  and connector state
calls above, so that we do have a connector before we can retry the
asyncronous work in case of any failure.



I don't quite understand this patch. You change the mhdp->connector to a
pointer, which is set at bridge_enable and cleared at bridge_disable.
Then you change the "mhdp->connector.dev" checks to "mhdp->connector".

So, now in e.g. cdns_mhdp_fw_cb(), we check for mhdp->connector, which
is set at bridge_enable(). Can we ever have the bridge enabled before
the fb has been loaded? What is the check even supposed to do there?

Another in cdns_mhdp_hpd_work(), it checks for mhdp->connector. So...
HPD code behaves differently based on if the bridge has been enabled or
not? What is it supposed to do?

Isn't the whole "if (mhdp->connector.dev)" code for the legacy
non-DRM_BRIDGE_ATTACH_NO_CONNECTOR case?

  Tomi


I misinterpreted your comment in v1[0] regarding finding the connector
from the current state in cdns_mhdp_modeset_retry_fn() and I missed
this. I was more focused on finding a connector for that function.

For the current code, in all the conditionals involving mhdp->connector,
we are entering else statements as connector is not initialised.
So I will just drop if statements in cdns_mhdp_fw_cb() and
cdns_mhdp_hpd_work() (like you said, its legacy case) while still having
mhdp->connector as pointer as we need it for
cdns_mhdp_modeset_retry_fn() and in cdns-mhdp8546-hdcp driver.

That should be okay?


[0]: 
https://lore.kernel.org/all/e76f94b9-b138-46e7-bb18-b33dd98c9...@ideasonboard.com/


Warm Regards,
Jayesh




Tomi,

One more thing here. Should this be squashed with the first patch as
this is sort of removing !(DRM_BRIDGE_ATTACH_NO_CONNECTOR) case and
associated changes?





Fixes: fb43aa0acdfd ("drm: bridge: Add support for Cadence MHDP8546 
DPI/DP bridge")

Signed-off-by: Jayesh Choudhary <j-choudh...@ti.com>
---
  .../drm/bridge/cadence/cdns-mhdp8546-core.c   | 28 +++++++++----------
  .../drm/bridge/cadence/cdns-mhdp8546-core.h   |  2 +-
  .../drm/bridge/cadence/cdns-mhdp8546-hdcp.c   |  8 +++---
  3 files changed, 19 insertions(+), 19 deletions(-)


diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c 
b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c

index 66bd916c2fe9..5388e62f230b 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c

@@ -740,7 +740,7 @@ static void cdns_mhdp_fw_cb(const struct firmware 
*fw, void *context)

      bridge_attached = mhdp->bridge_attached;
      spin_unlock(&mhdp->start_lock);
      if (bridge_attached) {
-        if (mhdp->connector.dev)
+        if (mhdp->connector)
              drm_kms_helper_hotplug_event(mhdp->bridge.dev);
          else

              drm_bridge_hpd_notify(&mhdp->bridge, 
cdns_mhdp_detect(mhdp));
@@ -1759,17 +1759,25 @@ static void cdns_mhdp_atomic_enable(struct 
drm_bridge *bridge,

      struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
      struct cdns_mhdp_bridge_state *mhdp_state;
      struct drm_crtc_state *crtc_state;
-    struct drm_connector *connector;
      struct drm_connector_state *conn_state;
      struct drm_bridge_state *new_state;
      const struct drm_display_mode *mode;
      u32 resp;
-    int ret;
+    int ret = 0;
      dev_dbg(mhdp->dev, "bridge enable\n");
      mutex_lock(&mhdp->link_mutex);
+    mhdp->connector = drm_atomic_get_new_connector_for_encoder(state,
+                                   bridge->encoder);
+    if (WARN_ON(!mhdp->connector))
+        goto out;
+

+    conn_state = drm_atomic_get_new_connector_state(state, 
mhdp->connector);

+    if (WARN_ON(!conn_state))
+        goto out;
+
      if (mhdp->plugged && !mhdp->link_up) {
          ret = cdns_mhdp_link_up(mhdp);
          if (ret < 0)

@@ -1789,15 +1797,6 @@ static void cdns_mhdp_atomic_enable(struct 
drm_bridge *bridge,

      cdns_mhdp_reg_write(mhdp, CDNS_DPTX_CAR,
                  resp | CDNS_VIF_CLK_EN | CDNS_VIF_CLK_RSTN);
-    connector = drm_atomic_get_new_connector_for_encoder(state,
-                                 bridge->encoder);
-    if (WARN_ON(!connector))
-        goto out;
-
-    conn_state = drm_atomic_get_new_connector_state(state, connector);
-    if (WARN_ON(!conn_state))
-        goto out;
-
      if (mhdp->hdcp_supported &&
          mhdp->hw_state == MHDP_HW_READY &&
          conn_state->content_protection ==

@@ -1857,6 +1856,7 @@ static void cdns_mhdp_atomic_disable(struct 
drm_bridge *bridge,

          cdns_mhdp_hdcp_disable(mhdp);
      mhdp->bridge_enabled = false;
+    mhdp->connector = NULL;
      cdns_mhdp_reg_read(mhdp, CDNS_DP_FRAMER_GLOBAL_CONFIG, &resp);
      resp &= ~CDNS_DP_FRAMER_EN;
      resp |= CDNS_DP_NO_VIDEO_MODE;

@@ -2157,7 +2157,7 @@ static void cdns_mhdp_modeset_retry_fn(struct 
work_struct *work)

      mhdp = container_of(work, typeof(*mhdp), modeset_retry_work);
-    conn = &mhdp->connector;
+    conn = mhdp->connector;
      /* Grab the locks before changing connector property */
      mutex_lock(&conn->dev->mode_config.mutex);

@@ -2234,7 +2234,7 @@ static void cdns_mhdp_hpd_work(struct 
work_struct *work)

      int ret;
      ret = cdns_mhdp_update_link_status(mhdp);
-    if (mhdp->connector.dev) {
+    if (mhdp->connector) {
          if (ret < 0)
              schedule_work(&mhdp->modeset_retry_work);
          else

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h 
b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h

index bad2fc0c7306..b297db53ba28 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.h
@@ -375,7 +375,7 @@ struct cdns_mhdp_device {
       */
      struct mutex link_mutex;
-    struct drm_connector connector;
+    struct drm_connector *connector;
      struct drm_bridge bridge;
      struct cdns_mhdp_link link;

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c 
b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c

index 42248f179b69..59f18c3281ef 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-hdcp.c

@@ -394,7 +394,7 @@ static int _cdns_mhdp_hdcp_disable(struct 
cdns_mhdp_device *mhdp)

      int ret;
      dev_dbg(mhdp->dev, "[%s:%d] HDCP is being disabled...\n",
-        mhdp->connector.name, mhdp->connector.base.id);
+        mhdp->connector->name, mhdp->connector->base.id);
      ret = cdns_mhdp_hdcp_set_config(mhdp, 0, false);

@@ -445,7 +445,7 @@ static int cdns_mhdp_hdcp_check_link(struct 
cdns_mhdp_device *mhdp)

      dev_err(mhdp->dev,
          "[%s:%d] HDCP link failed, retrying authentication\n",
-        mhdp->connector.name, mhdp->connector.base.id);
+        mhdp->connector->name, mhdp->connector->base.id);
      ret = _cdns_mhdp_hdcp_disable(mhdp);
      if (ret) {

@@ -487,13 +487,13 @@ static void cdns_mhdp_hdcp_prop_work(struct 
work_struct *work)

      struct cdns_mhdp_device *mhdp = container_of(hdcp,
                               struct cdns_mhdp_device,
                               hdcp);
-    struct drm_device *dev = mhdp->connector.dev;
+    struct drm_device *dev = mhdp->connector->dev;
      struct drm_connector_state *state;
      drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
      mutex_lock(&mhdp->hdcp.mutex);
      if (mhdp->hdcp.value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
-        state = mhdp->connector.state;
+        state = mhdp->connector->state;
          state->content_protection = mhdp->hdcp.value;
      }
      mutex_unlock(&mhdp->hdcp.mutex);

























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