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

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Date:   Wed, 2 May 2018 13:48:43 +0200
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Jagan Teki <jagan@...rulasolutions.com>
Cc:     Chen-Yu Tsai <wens@...e.org>, Icenowy Zheng <icenowy@...c.io>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        Michael Trimarchi <michael@...rulasolutions.com>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH 15/21] drm: sun4i: add support for HVCC regulator for DWC
 HDMI glue

On Mon, Apr 30, 2018 at 05:10:52PM +0530, Jagan Teki wrote:
> From: Icenowy Zheng <icenowy@...c.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@...c.io>
> Signed-off-by: Jagan Teki <jagan@...rulasolutions.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 :)

>  	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

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

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