drm/omap: hdmi4: Rework EDID read to isolate data read

In preparation of adding DRM bridge support to the hdmi4 encoder code,
rework the EDID read to isolate data read.

The hdmi_read_edid() function is the main entry point. It performs all
initialisation steps required prior to reading the EDID (such as
ensuring the device is powered on), as well as corresponding cleanup
steps afterwards. EDID read itself is handled by hdmi_read_edid_data()
that calls the hdmi4_core_ddc_read() function to read individual blocks.

This new code architecture will allow reusing hdmi_read_edid() and
hdmi4_core_ddc_read() for the drm_bridge EDID read implementation, while
swapping out hdmi_read_edid_data() for the DRM drm_do_get_edid()
function.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-30-laurent.pinchart@ideasonboard.com

1 files changed, 61 insertions, 33 deletions

diff --git a/drivers/gpu/drm/omapdrm/dss/hdmi4.c b/drivers/gpu/drm/omapdrm/dss/hdmi4.c
index e15fa3862922..37536b9f3114 100644
--- a/drivers/gpu/drm/omapdrm/dss/hdmi4.c
+++ b/drivers/gpu/drm/omapdrm/dss/hdmi4.c
@@ -272,23 +272,6 @@ static int hdmi_dump_regs(struct seq_file *s, void *p)
 	return 0;
 }
 
-static int read_edid(struct omap_hdmi *hdmi, u8 *buf, int len)
-{
-	int r;
-
-	mutex_lock(&hdmi->lock);
-
-	r = hdmi_runtime_get(hdmi);
-	BUG_ON(r);
-
-	r = hdmi4_read_edid(&hdmi->core,  buf, len);
-
-	hdmi_runtime_put(hdmi);
-	mutex_unlock(&hdmi->lock);
-
-	return r;
-}
-
 static void hdmi_start_audio_stream(struct omap_hdmi *hd)
 {
 	hdmi_wp_audio_enable(&hd->wp, true);
@@ -407,10 +390,8 @@ static void hdmi_disconnect(struct omap_dss_device *src,
 
 #define MAX_EDID	512
 
-static struct edid *hdmi_read_edid(struct omap_dss_device *dssdev)
+static struct edid *hdmi_read_edid_data(struct omap_hdmi *hdmi)
 {
-	struct omap_hdmi *hdmi = dssdev_to_hdmi(dssdev);
-	bool need_enable;
 	u8 *edid;
 	int r;
 
@@ -418,32 +399,79 @@ static struct edid *hdmi_read_edid(struct omap_dss_device *dssdev)
 	if (!edid)
 		return NULL;
 
+	r = hdmi4_core_ddc_read(&hdmi->core, edid, 0, EDID_LENGTH);
+	if (r)
+		goto error;
+
+	if (edid[0x7e] > 0) {
+		char checksum = 0;
+		unsigned int i;
+
+		r = hdmi4_core_ddc_read(&hdmi->core, edid + EDID_LENGTH, 1,
+					EDID_LENGTH);
+		if (r)
+			goto error;
+
+		for (i = 0; i < EDID_LENGTH; ++i)
+			checksum += edid[EDID_LENGTH + i];
+
+		if (checksum != 0) {
+			DSSERR("E-EDID checksum failed!!\n");
+			goto error;
+		}
+	}
+
+	return (struct edid *)edid;
+
+error:
+	kfree(edid);
+	return NULL;
+}
+
+static struct edid *hdmi_read_edid(struct omap_dss_device *dssdev)
+{
+	struct omap_hdmi *hdmi = dssdev_to_hdmi(dssdev);
+	struct edid *edid = NULL;
+	unsigned int cec_addr;
+	bool need_enable;
+	int r;
+
 	need_enable = hdmi->core_enabled == false;
 
 	if (need_enable) {
 		r = hdmi4_core_enable(&hdmi->core);
-		if (r) {
-			kfree(edid);
+		if (r)
 			return NULL;
-		}
 	}
 
-	r = read_edid(hdmi, edid, MAX_EDID);
-	if (r < 0) {
-		kfree(edid);
-		edid = NULL;
-	} else {
-		unsigned int cec_addr;
+	mutex_lock(&hdmi->lock);
+	r = hdmi_runtime_get(hdmi);
+	BUG_ON(r);
+
+	r = hdmi4_core_ddc_init(&hdmi->core);
+	if (r)
+		goto done;
 
-		cec_addr = r >= 256 ? cec_get_edid_phys_addr(edid, r, NULL)
-			 : CEC_PHYS_ADDR_INVALID;
-		hdmi4_cec_set_phys_addr(&hdmi->core, cec_addr);
+	edid = hdmi_read_edid_data(hdmi);
+
+done:
+	hdmi_runtime_put(hdmi);
+	mutex_unlock(&hdmi->lock);
+
+	if (edid && edid->extensions) {
+		unsigned int len = (edid->extensions + 1) * EDID_LENGTH;
+
+		cec_addr = cec_get_edid_phys_addr((u8 *)edid, len, NULL);
+	} else {
+		cec_addr = CEC_PHYS_ADDR_INVALID;
 	}
 
+	hdmi4_cec_set_phys_addr(&hdmi->core, cec_addr);
+
 	if (need_enable)
 		hdmi4_core_disable(&hdmi->core);
 
-	return (struct edid *)edid;
+	return edid;
 }
 
 static void hdmi_lost_hotplug(struct omap_dss_device *dssdev)