Re: [PATCH 15/21] drm: sun4i: add support for HVCC regulator for DWC HDMI glue

Icenowy Zheng
2018-05-02T11:52:15Z

于 2018年5月2日 GMT+08:00 下午7:48:43, Maxime Ripard <maxime.ripard@bootlin.com> 写到:
>On Mon, Apr 30, 2018 at 05:10:52PM +0530, Jagan Teki wrote:
>> From: Icenowy Zheng <icenowy@aosc.io>
>>
>> Allwinner SoCs with DWC HDMI controller have a "HVCC" power pin for
>the
>> 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
>> dedicated regulator to power it, the default dummy regulator is used.
>>
>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
>> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
>> ---
>> 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
>> 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,
>> 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.

>
>> 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,
>> 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,
>> 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