From: Pierre-Hugues Husson <phh@phh.me>
Date: Sat, 25 Nov 2017 21:18:44 +0100
Subject: drm/bridge: synopsys/dw-hdmi: Enable cec clock
Git-commit: ebe32c3e282a62974b190b9d514864fc0d56716e
Patch-mainline: v4.15-rc2
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Support the "cec" optional clock. The documentation already mentions "cec"
optional clock and it is used by several boards, but currently the driver
doesn't enable it, thus preventing cec from working on those boards.

And even worse: a /dev/cecX device will appear for those boards, but it
won't be functioning without configuring this clock.

Changes:
v4:
- Change commit message to stress the importance of this patch

v3:
- Drop useless braces

v2:
- Separate ENOENT errors from others
- Propagate other errors (especially -EPROBE_DEFER)

Signed-off-by: Pierre-Hugues Husson <phh@phh.me>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20171125201844.11353-1-phh@phh.me

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c |   25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -138,6 +138,7 @@ struct dw_hdmi {
 	struct device *dev;
 	struct clk *isfr_clk;
 	struct clk *iahb_clk;
+	struct clk *cec_clk;
 	struct dw_hdmi_i2c *i2c;
 
 	struct hdmi_data_info hdmi_data;
@@ -2382,6 +2383,26 @@ __dw_hdmi_probe(struct platform_device *
 		goto err_isfr;
 	}
 
+	hdmi->cec_clk = devm_clk_get(hdmi->dev, "cec");
+	if (PTR_ERR(hdmi->cec_clk) == -ENOENT) {
+		hdmi->cec_clk = NULL;
+	} else if (IS_ERR(hdmi->cec_clk)) {
+		ret = PTR_ERR(hdmi->cec_clk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(hdmi->dev, "Cannot get HDMI cec clock: %d\n",
+				ret);
+
+		hdmi->cec_clk = NULL;
+		goto err_iahb;
+	} else {
+		ret = clk_prepare_enable(hdmi->cec_clk);
+		if (ret) {
+			dev_err(hdmi->dev, "Cannot enable HDMI cec clock: %d\n",
+				ret);
+			goto err_iahb;
+		}
+	}
+
 	/* Product and revision IDs */
 	hdmi->version = (hdmi_readb(hdmi, HDMI_DESIGN_ID) << 8)
 		      | (hdmi_readb(hdmi, HDMI_REVISION_ID) << 0);
@@ -2518,6 +2539,8 @@ err_iahb:
 		cec_notifier_put(hdmi->cec_notifier);
 
 	clk_disable_unprepare(hdmi->iahb_clk);
+	if (hdmi->cec_clk)
+		clk_disable_unprepare(hdmi->cec_clk);
 err_isfr:
 	clk_disable_unprepare(hdmi->isfr_clk);
 err_res:
@@ -2541,6 +2564,8 @@ static void __dw_hdmi_remove(struct dw_h
 
 	clk_disable_unprepare(hdmi->iahb_clk);
 	clk_disable_unprepare(hdmi->isfr_clk);
+	if (hdmi->cec_clk)
+		clk_disable_unprepare(hdmi->cec_clk);
 
 	if (hdmi->i2c)
 		i2c_del_adapter(&hdmi->i2c->adap);