Re: [PATCH v7 drm-dp 5/9] drm/hisilicon/hibmc: Getting connector info and EDID by using AUX channel

[Yongbang Shi]

On Mon, 24 Mar 2025, Yongbang Shi <shiyongb...@huawei.com> wrote:

On Wed, 19 Mar 2025, Yongbang Shi <shiyongb...@huawei.com> wrote:

From: Baihan Li <libai...@huawei.com>

Add registering drm_aux and use it to get connector edid with drm
functions. Add ddc channel in connector initialization to put drm_aux
in drm_connector.

Signed-off-by: Baihan Li <libai...@huawei.com>
Signed-off-by: Yongbang Shi <shiyongb...@huawei.com>
Reviewed-by: Dmitry Baryshkov <dmitry.barysh...@linaro.org>
---
ChangeLog:
v6 -> v7:
    - add if statement about drm aux in hibmc_dp_connector_get_modes(), 
suggested by Jani Nikula

I don't understand this, and I did not suggest such a thing.

BR,
Jani.

Hi Jani,

Is the modification of v8 correct?

I never received that for whatever reason.

Here's the link: 
https://lore.kernel.org/all/20250320101455.2538835-1-shiyongb...@huawei.com/

v5 -> v6:
    - move the detect_ctx() to the patch 7/9.
v2 -> v3:
    - Capitalized EDID and AUX, suggested by Dmitry Baryshkov.
v1 -> v2:
    - deleting type conversion, suggested by Dmitry Baryshkov.
    - deleting hibmc_dp_connector_get_modes() and using 
drm_connector_helper_get_modes(), suggested by Dmitry Baryshkov.
---
   drivers/gpu/drm/hisilicon/hibmc/dp/dp_aux.c   |  3 +-
   .../gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c    | 35 ++++++++++++++++---
   .../gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h   |  5 +++
   3 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_aux.c 
b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_aux.c
index ded9e7ce887a..e0bb9b14d9d8 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_aux.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_aux.c
@@ -161,7 +161,8 @@ void hibmc_dp_aux_init(struct hibmc_dp *dp)
                                 HIBMC_DP_MIN_PULSE_NUM);

dp->aux.transfer = hibmc_dp_aux_xfer;

-       dp->aux.is_remote = 0;
+       dp->aux.name = kasprintf(GFP_KERNEL, "HIBMC DRM dp aux");
+       dp->aux.drm_dev = dp->drm_dev;
        drm_dp_aux_init(&dp->aux);
        dp->dp_dev->aux = &dp->aux;
   }
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c 
b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
index 603d6b198a54..0256724d8b9b 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
@@ -15,11 +15,20 @@

static int hibmc_dp_connector_get_modes(struct drm_connector *connector)

   {
+       struct hibmc_dp *dp = to_hibmc_dp(connector);
+       const struct drm_edid *drm_edid;
        int count;

- count = drm_add_modes_noedid(connector, connector->dev->mode_config.max_width,

-                                    connector->dev->mode_config.max_height);
-       drm_set_preferred_mode(connector, 1024, 768); // temporary 
implementation
+       if (!dp->aux.name)
+               return 0;
+
+       drm_edid = drm_edid_read_ddc(connector, &dp->aux.ddc);
+
+       drm_edid_connector_update(connector, drm_edid);
+
+       count = drm_edid_connector_add_modes(connector);
+
+       drm_edid_free(drm_edid);

return count;

   }
@@ -28,12 +37,28 @@ static const struct drm_connector_helper_funcs 
hibmc_dp_conn_helper_funcs = {
        .get_modes = hibmc_dp_connector_get_modes,
   };

+static int hibmc_dp_late_register(struct drm_connector *connector)

+{
+       struct hibmc_dp *dp = to_hibmc_dp(connector);
+
+       return drm_dp_aux_register(&dp->aux);
+}
+
+static void hibmc_dp_early_unregister(struct drm_connector *connector)
+{
+       struct hibmc_dp *dp = to_hibmc_dp(connector);
+
+       drm_dp_aux_unregister(&dp->aux);
+}
+
   static const struct drm_connector_funcs hibmc_dp_conn_funcs = {
        .reset = drm_atomic_helper_connector_reset,
        .fill_modes = drm_helper_probe_single_connector_modes,
        .destroy = drm_connector_cleanup,
        .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+       .late_register = hibmc_dp_late_register,
+       .early_unregister = hibmc_dp_early_unregister,
   };

static inline int hibmc_dp_prepare(struct hibmc_dp *dp, struct drm_display_mode *mode)

@@ -103,8 +128,8 @@ int hibmc_dp_init(struct hibmc_drm_private *priv)

drm_encoder_helper_add(encoder, &hibmc_dp_encoder_helper_funcs); - ret = drm_connector_init(dev, connector, &hibmc_dp_conn_funcs,

-                                DRM_MODE_CONNECTOR_DisplayPort);
+       ret = drm_connector_init_with_ddc(dev, connector, &hibmc_dp_conn_funcs,
+                                         DRM_MODE_CONNECTOR_DisplayPort, 
&dp->aux.ddc);
        if (ret) {
                drm_err(dev, "init dp connector failed: %d\n", ret);
                return ret;
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h 
b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
index d982f1e4b958..3ddd71aada66 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
@@ -47,6 +47,11 @@ static inline struct hibmc_vdac *to_hibmc_vdac(struct 
drm_connector *connector)
        return container_of(connector, struct hibmc_vdac, connector);
   }

+static inline struct hibmc_dp *to_hibmc_dp(struct drm_connector *connector)

+{
+       return container_of(connector, struct hibmc_dp, connector);
+}
+
   static inline struct hibmc_drm_private *to_hibmc_drm_private(struct 
drm_device *dev)
   {
        return container_of(dev, struct hibmc_drm_private, dev);