linux-kernel - Re: [PATCH] drm/sun4i: hdmi: add support for ddc-i2c-bus property

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Date:   Mon, 11 Mar 2019 16:47:02 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Mans Rullgard <mans@...sr.com>
Cc:     David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/sun4i: hdmi: add support for ddc-i2c-bus property

Hi!

On Mon, Mar 11, 2019 at 01:47:13PM +0000, Mans Rullgard wrote:
> Sometimes it is desirabled to use a separate i2c controller for ddc
> access.  This adds support for the ddc-i2c-bus property of the
> hdmi-connector node, using the specified controller if provided.
> 
> Signed-off-by: Mans Rullgard <mans@...sr.com>
> ---
>  drivers/gpu/drm/sun4i/sun4i_hdmi.h     |  1 +
>  drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 37 +++++++++++++++++++++++---
>  2 files changed, 35 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi.h b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
> index b685ee11623d..b08c4453d47c 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi.h
> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
> @@ -269,6 +269,7 @@ struct sun4i_hdmi {
>  	struct clk		*tmds_clk;
>  
>  	struct i2c_adapter	*i2c;
> +	struct i2c_adapter	*ddc_i2c;
>  
>  	/* Regmap fields for I2C adapter */
>  	struct regmap_field	*field_ddc_en;
> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> index 061d2e0d9011..5b2fac79f5d6 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> @@ -212,7 +212,7 @@ static int sun4i_hdmi_get_modes(struct drm_connector *connector)
>  	struct edid *edid;
>  	int ret;
>  
> -	edid = drm_get_edid(connector, hdmi->i2c);
> +	edid = drm_get_edid(connector, hdmi->ddc_i2c ?: hdmi->i2c);

You can't test whether ddc_i2c is NULL or not...

>  	if (!edid)
>  		return 0;
>  
> @@ -228,6 +228,28 @@ static int sun4i_hdmi_get_modes(struct drm_connector *connector)
>  	return ret;
>  }
>  
> +static struct i2c_adapter *sun4i_hdmi_get_ddc(struct device *dev)
> +{
> +	struct device_node *phandle, *remote;
> +	struct i2c_adapter *ddc;
> +
> +	remote = of_graph_get_remote_node(dev->of_node, 1, -1);
> +	if (!remote)
> +		return ERR_PTR(-EINVAL);
> +
> +	phandle = of_parse_phandle(remote, "ddc-i2c-bus", 0);
> +	of_node_put(remote);
> +	if (!phandle)
> +		return NULL;
> +
> +	ddc = of_get_i2c_adapter_by_node(phandle);
> +	of_node_put(phandle);
> +	if (!ddc)
> +		return ERR_PTR(-EPROBE_DEFER);
> +
> +	return ddc;

... Since even in (most) error cases you're returning a !NULL pointer.

> +}
> +
>  static const struct drm_connector_helper_funcs sun4i_hdmi_connector_helper_funcs = {
>  	.get_modes	= sun4i_hdmi_get_modes,
>  };
> @@ -575,6 +597,12 @@ static int sun4i_hdmi_bind(struct device *dev, struct device *master,
>  		goto err_disable_mod_clk;
>  	}
>  
> +	hdmi->ddc_i2c = sun4i_hdmi_get_ddc(dev);
> +	if (IS_ERR(hdmi->ddc_i2c)) {
> +		ret = PTR_ERR(hdmi->ddc_i2c);
> +		goto err_del_i2c_adapter;
> +	}
> +
>  	drm_encoder_helper_add(&hdmi->encoder,
>  			       &sun4i_hdmi_helper_funcs);
>  	ret = drm_encoder_init(drm,
> @@ -584,14 +612,14 @@ static int sun4i_hdmi_bind(struct device *dev, struct device *master,
>  			       NULL);
>  	if (ret) {
>  		dev_err(dev, "Couldn't initialise the HDMI encoder\n");
> -		goto err_del_i2c_adapter;
> +		goto err_put_ddc_i2c;
>  	}
>  
>  	hdmi->encoder.possible_crtcs = drm_of_find_possible_crtcs(drm,
>  								  dev->of_node);
>  	if (!hdmi->encoder.possible_crtcs) {
>  		ret = -EPROBE_DEFER;
> -		goto err_del_i2c_adapter;
> +		goto err_put_ddc_i2c;
>  	}
>  
>  #ifdef CONFIG_DRM_SUN4I_HDMI_CEC
> @@ -630,6 +658,8 @@ static int sun4i_hdmi_bind(struct device *dev, struct device *master,
>  err_cleanup_connector:
>  	cec_delete_adapter(hdmi->cec_adap);
>  	drm_encoder_cleanup(&hdmi->encoder);
> +err_put_ddc_i2c:
> +	i2c_put_adapter(hdmi->ddc_i2c);
>  err_del_i2c_adapter:
>  	i2c_del_adapter(hdmi->i2c);
>  err_disable_mod_clk:
> @@ -650,6 +680,7 @@ static void sun4i_hdmi_unbind(struct device *dev, struct device *master,
>  	drm_connector_cleanup(&hdmi->connector);
>  	drm_encoder_cleanup(&hdmi->encoder);
>  	i2c_del_adapter(hdmi->i2c);
> +	i2c_put_adapter(hdmi->ddc_i2c);
>  	clk_disable_unprepare(hdmi->mod_clk);
>  	clk_disable_unprepare(hdmi->bus_clk);
>  }
> -- 
> 2.21.0
>

It looks good otherwise, thanks!
Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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