Sometimes it is desirabled to use a separate i2c controller for ddc
access.  This adds support for the ddc-i2c-bus property of the
hdmi-connector node, using the specified controller if provided.

Signed-off-by: Mans Rullgard <m...@mansr.com>
---
Changed in v2:
- Return ERR_PTR(-ENODEV) instead of NULL when property is absent
---
 drivers/gpu/drm/sun4i/sun4i_hdmi.h     |  1 +
 drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 40 ++++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi.h 
b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
index b685ee11623d..b08c4453d47c 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi.h
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
@@ -269,6 +269,7 @@ struct sun4i_hdmi {
        struct clk              *tmds_clk;
 
        struct i2c_adapter      *i2c;
+       struct i2c_adapter      *ddc_i2c;
 
        /* Regmap fields for I2C adapter */
        struct regmap_field     *field_ddc_en;
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c 
b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
index 416da5376701..a99523e9651f 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
@@ -216,7 +216,7 @@ static int sun4i_hdmi_get_modes(struct drm_connector 
*connector)
        struct edid *edid;
        int ret;
 
-       edid = drm_get_edid(connector, hdmi->i2c);
+       edid = drm_get_edid(connector, hdmi->ddc_i2c ?: hdmi->i2c);
        if (!edid)
                return 0;
 
@@ -232,6 +232,28 @@ static int sun4i_hdmi_get_modes(struct drm_connector 
*connector)
        return ret;
 }
 
+static struct i2c_adapter *sun4i_hdmi_get_ddc(struct device *dev)
+{
+       struct device_node *phandle, *remote;
+       struct i2c_adapter *ddc;
+
+       remote = of_graph_get_remote_node(dev->of_node, 1, -1);
+       if (!remote)
+               return ERR_PTR(-EINVAL);
+
+       phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
+       of_node_put(remote);
+       if (!phandle)
+               return ERR_PTR(-ENODEV);
+
+       ddc = of_get_i2c_adapter_by_node(phandle);
+       of_node_put(phandle);
+       if (!ddc)
+               return ERR_PTR(-EPROBE_DEFER);
+
+       return ddc;
+}
+
 static const struct drm_connector_helper_funcs 
sun4i_hdmi_connector_helper_funcs = {
        .get_modes      = sun4i_hdmi_get_modes,
 };
@@ -579,6 +601,15 @@ static int sun4i_hdmi_bind(struct device *dev, struct 
device *master,
                goto err_disable_mod_clk;
        }
 
+       hdmi->ddc_i2c = sun4i_hdmi_get_ddc(dev);
+       if (IS_ERR(hdmi->ddc_i2c)) {
+               ret = PTR_ERR(hdmi->ddc_i2c);
+               if (ret == -ENODEV)
+                       hdmi->ddc_i2c = NULL;
+               else
+                       goto err_del_i2c_adapter;
+       }
+
        drm_encoder_helper_add(&hdmi->encoder,
                               &sun4i_hdmi_helper_funcs);
        ret = drm_encoder_init(drm,
@@ -588,14 +619,14 @@ static int sun4i_hdmi_bind(struct device *dev, struct 
device *master,
                               NULL);
        if (ret) {
                dev_err(dev, "Couldn't initialise the HDMI encoder\n");
-               goto err_del_i2c_adapter;
+               goto err_put_ddc_i2c;
        }
 
        hdmi->encoder.possible_crtcs = drm_of_find_possible_crtcs(drm,
                                                                  dev->of_node);
        if (!hdmi->encoder.possible_crtcs) {
                ret = -EPROBE_DEFER;
-               goto err_del_i2c_adapter;
+               goto err_put_ddc_i2c;
        }
 
 #ifdef CONFIG_DRM_SUN4I_HDMI_CEC
@@ -634,6 +665,8 @@ static int sun4i_hdmi_bind(struct device *dev, struct 
device *master,
 err_cleanup_connector:
        cec_delete_adapter(hdmi->cec_adap);
        drm_encoder_cleanup(&hdmi->encoder);
+err_put_ddc_i2c:
+       i2c_put_adapter(hdmi->ddc_i2c);
 err_del_i2c_adapter:
        i2c_del_adapter(hdmi->i2c);
 err_disable_mod_clk:
@@ -654,6 +687,7 @@ static void sun4i_hdmi_unbind(struct device *dev, struct 
device *master,
        drm_connector_cleanup(&hdmi->connector);
        drm_encoder_cleanup(&hdmi->encoder);
        i2c_del_adapter(hdmi->i2c);
+       i2c_put_adapter(hdmi->ddc_i2c);
        clk_disable_unprepare(hdmi->mod_clk);
        clk_disable_unprepare(hdmi->bus_clk);
 }
-- 
2.21.0

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