于 2018年5月2日 GMT+08:00 下午7:48:43, Maxime Ripard [off-list ref] 写到:

On Mon, Apr 30, 2018 at 05:10:52PM +0530, Jagan Teki wrote:

quoted

From: Icenowy Zheng <redacted>

Allwinner SoCs with DWC HDMI controller have a "HVCC" power pin for

the

quoted

HDMI part, and on some boards it's connected to a dedicated regulator
rather than the main 3.3v.

Add support for optional HVCC regulator. For boards that doesn't use

a

quoted

dedicated regulator to power it, the default dummy regulator is used.

Signed-off-by: Icenowy Zheng <redacted>
Signed-off-by: Jagan Teki <jagan-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org>
---
 drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c | 14 ++++++++++++++
 drivers/gpu/drm/sun4i/sun8i_dw_hdmi.h |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c

b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c

quoted

index 9f40a44b456b..7c33faff7ad4 100644

--- a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
+++ b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c

@@ -73,6 +73,12 @@ static int sun8i_dw_hdmi_bind(struct device *dev,

struct device *master,

quoted

 	if (encoder->possible_crtcs == 0)
 		return -EPROBE_DEFER;
 
+	hdmi->vcc_hdmi = devm_regulator_get(dev, "hvcc");
+	if (IS_ERR(hdmi->vcc_hdmi)) {
+		dev_err(dev, "Could not get HDMI power supply\n");
+		return PTR_ERR(hdmi->vcc_hdmi);
+	}
+

You're not making it optional here, unlike what your commit log
says. Not that I'm fine with both, but we need to be consistent :)

If it's not set, regulator subsystem will generate a dummy
regulator as a spaceholder, except using the exclusive variant
of the function.

The word "optional" is from DT perspectove, as it's possible that
it's bound to some critical regulators.

quoted

 	hdmi->rst_ctrl = devm_reset_control_get(dev, "ctrl");
 	if (IS_ERR(hdmi->rst_ctrl)) {
 		dev_err(dev, "Could not get ctrl reset control\n");

@@ -91,6 +97,12 @@ static int sun8i_dw_hdmi_bind(struct device *dev,

struct device *master,

quoted

 		return ret;
 	}
 
+	ret = regulator_enable(hdmi->vcc_hdmi);
+	if (ret) {
+		dev_err(dev, "Cannot enable HDMI power supply\n");
+		goto err_disable_vcc;
+	}
+
 	ret = clk_prepare_enable(hdmi->clk_tmds);
 	if (ret) {
 		dev_err(dev, "Could not enable tmds clock\n");

@@ -143,6 +155,8 @@ static int sun8i_dw_hdmi_bind(struct device *dev,

struct device *master,

quoted

 	clk_disable_unprepare(hdmi->clk_tmds);
 err_assert_ctrl_reset:
 	reset_control_assert(hdmi->rst_ctrl);
+err_disable_vcc:
+	regulator_disable(hdmi->vcc_hdmi);

The err_disable_vcc label will disable the regulator, but if there's
an error in regulator_enable, it will disable it while it wasn't
enabled in the first place, which is not really something we want to
do.

Maxime

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