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Subject[PATCH v3 1/2] drm/imx: imx-ldb: Add DDC support
Date
From: Steve Longerbeam <steve_longerbeam@mentor.com>

Add support for reading EDID over Display Data Channel. If no DDC
adapter is available, falls back to hardcoded EDID or display-timings
node as before.

Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Akshay Bhat <akshay.bhat@timesys.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
---

Hi Philipp,

I have addressed all your comments on v2 Patch.

Thanks,
Akshay

v3:
Move ddc_node pointer definition
Warn and perform a probe deferral on failing to get ddc i2c adapter by node

v2:
Rebase to 4.6-rc5
Add check for channel->panel before fallback to display-timings node

drivers/gpu/drm/imx/imx-ldb.c | 42 ++++++++++++++++++++++++++++++++++--------
1 file changed, 34 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index a58eee5..f506e8d 100644
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -59,6 +59,7 @@ struct imx_ldb_channel {
struct drm_encoder encoder;
struct drm_panel *panel;
struct device_node *child;
+ struct i2c_adapter *ddc;
int chno;
void *edid;
int edid_len;
@@ -107,6 +108,9 @@ static int imx_ldb_connector_get_modes(struct drm_connector *connector)
return num_modes;
}

+ if (!imx_ldb_ch->edid && imx_ldb_ch->ddc)
+ imx_ldb_ch->edid = drm_get_edid(connector, imx_ldb_ch->ddc);
+
if (imx_ldb_ch->edid) {
drm_mode_connector_update_edid_property(connector,
imx_ldb_ch->edid);
@@ -553,6 +557,7 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)

for_each_child_of_node(np, child) {
struct imx_ldb_channel *channel;
+ struct device_node *ddc_node;
struct device_node *port;

ret = of_property_read_u32(child, "reg", &i);
@@ -595,14 +600,34 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
}
}

- edidp = of_get_property(child, "edid", &channel->edid_len);
- if (edidp) {
- channel->edid = kmemdup(edidp, channel->edid_len,
- GFP_KERNEL);
- } else if (!channel->panel) {
- ret = of_get_drm_display_mode(child, &channel->mode, 0);
- if (!ret)
- channel->mode_valid = 1;
+ ddc_node = of_parse_phandle(child, "ddc-i2c-bus", 0);
+ if (ddc_node) {
+ channel->ddc = of_find_i2c_adapter_by_node(ddc_node);
+ of_node_put(ddc_node);
+ if (!channel->ddc) {
+ dev_warn(dev, "failed to get ddc i2c adapter\n");
+ return -EPROBE_DEFER;
+ }
+ }
+
+ if (!channel->ddc) {
+ /* if no DDC available, fallback to hardcoded EDID */
+ dev_dbg(dev, "no ddc available\n");
+
+ edidp = of_get_property(child, "edid",
+ &channel->edid_len);
+ if (edidp) {
+ channel->edid = kmemdup(edidp,
+ channel->edid_len,
+ GFP_KERNEL);
+ } else if (!channel->panel) {
+ /* fallback to display-timings node */
+ ret = of_get_drm_display_mode(child,
+ &channel->mode,
+ 0);
+ if (!ret)
+ channel->mode_valid = 1;
+ }
}

channel->bus_format = of_get_bus_format(dev, child);
@@ -647,6 +672,7 @@ static void imx_ldb_unbind(struct device *dev, struct device *master,
channel->encoder.funcs->destroy(&channel->encoder);

kfree(channel->edid);
+ i2c_put_adapter(channel->ddc);
}
}

--
2.8.1
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