[RFC PATCH v2] staging: imx-hdmi: use rx sense status for plug detection if hpd is unreliable

[Shawn Guo]

On Fri, Jan 10, 2014 at 03:22:24PM +0100, Philipp Zabel wrote:
> Due to the voltage divider on the HPD line, the HDMI connector on
> imx6q-sabrelite doesn't reliably detect connected DVI monitors.
> This patch allows to use the RX_SENSE0 signal as a workaround when
> enabled by a boolean device tree property 'hpd-unreliable'.

If it's a fsl/imx specific property, it should have a 'fsl,' prefix.
It should be added into binding doc.  Oh, we do not even have a binding
doc for this imx-hdmi yet.

Shawn

> 
> Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
> ---
> This patch is based on Russell's recent 46-patch imx-drm cleanup series.
> Changes since v1:
>  - Store the status and polarity bits in struct imx_hdmi
> ---
>  drivers/staging/imx-drm/imx-hdmi.c | 36 ++++++++++++++++++++++++++----------
>  1 file changed, 26 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/staging/imx-drm/imx-hdmi.c b/drivers/staging/imx-drm/imx-hdmi.c
> index fb3177d..62cb531 100644
> --- a/drivers/staging/imx-drm/imx-hdmi.c
> +++ b/drivers/staging/imx-drm/imx-hdmi.c
> @@ -140,6 +140,9 @@ struct imx_hdmi {
>  	struct regmap *regmap;
>  	struct i2c_adapter *ddc;
>  	void __iomem *regs;
> +	u8 sink_detect_polarity;
> +	u8 sink_detect_status;
> +	u8 sink_detect_mask;
>  
>  	unsigned int sample_rate;
>  	int ratio;
> @@ -1317,10 +1320,10 @@ static int imx_hdmi_fb_registered(struct imx_hdmi *hdmi)
>  		    HDMI_PHY_I2CM_CTLINT_ADDR);
>  
>  	/* enable cable hot plug irq */
> -	hdmi_writeb(hdmi, (u8)~HDMI_PHY_HPD, HDMI_PHY_MASK0);
> +	hdmi_writeb(hdmi, hdmi->sink_detect_mask, HDMI_PHY_MASK0);
>  
>  	/* Clear Hotplug interrupts */
> -	hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD, HDMI_IH_PHY_STAT0);
> +	hdmi_writeb(hdmi, hdmi->sink_detect_status, HDMI_IH_PHY_STAT0);
>  
>  	return 0;
>  }
> @@ -1392,6 +1395,7 @@ static enum drm_connector_status imx_hdmi_connector_detect(struct drm_connector
>  {
>  	struct imx_hdmi *hdmi = container_of(connector, struct imx_hdmi,
>  					     connector);
> +
>  	return hdmi->connector_status;
>  }
>  
> @@ -1530,18 +1534,20 @@ static irqreturn_t imx_hdmi_irq(int irq, void *dev_id)
>  
>  	phy_int_pol = hdmi_readb(hdmi, HDMI_PHY_POL0);
>  
> -	if (intr_stat & HDMI_IH_PHY_STAT0_HPD) {
> -		if (phy_int_pol & HDMI_PHY_HPD) {
> +	if (intr_stat & hdmi->sink_detect_status) {
> +		int pol_bit = hdmi->sink_detect_polarity;
> +
> +		if (phy_int_pol & pol_bit) {
>  			dev_dbg(hdmi->dev, "EVENT=plugin\n");
>  
> -			hdmi_modb(hdmi, 0, HDMI_PHY_HPD, HDMI_PHY_POL0);
> +			hdmi_modb(hdmi, 0, pol_bit, HDMI_PHY_POL0);
>  
>  			hdmi->connector_status = connector_status_connected;
>  			imx_hdmi_poweron(hdmi);
>  		} else {
>  			dev_dbg(hdmi->dev, "EVENT=plugout\n");
>  
> -			hdmi_modb(hdmi, HDMI_PHY_HPD, HDMI_PHY_HPD, HDMI_PHY_POL0);
> +			hdmi_modb(hdmi, pol_bit, pol_bit, HDMI_PHY_POL0);
>  
>  			hdmi->connector_status = connector_status_disconnected;
>  			imx_hdmi_poweroff(hdmi);
> @@ -1550,7 +1556,7 @@ static irqreturn_t imx_hdmi_irq(int irq, void *dev_id)
>  	}
>  
>  	hdmi_writeb(hdmi, intr_stat, HDMI_IH_PHY_STAT0);
> -	hdmi_writeb(hdmi, ~HDMI_IH_PHY_STAT0_HPD, HDMI_IH_MUTE_PHY_STAT0);
> +	hdmi_writeb(hdmi, ~hdmi->sink_detect_status, HDMI_IH_MUTE_PHY_STAT0);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -1702,14 +1708,24 @@ static int imx_hdmi_bind(struct device *dev, struct device *master, void *data)
>  	 */
>  	hdmi_init_clk_regenerator(hdmi);
>  
> +	hdmi->sink_detect_status = HDMI_IH_PHY_STAT0_HPD;
> +	hdmi->sink_detect_polarity = HDMI_PHY_HPD;
> +	hdmi->sink_detect_mask = ~HDMI_PHY_HPD;
> +
> +	if (of_property_read_bool(np, "hpd-unreliable")) {
> +		hdmi->sink_detect_status = HDMI_IH_PHY_STAT0_RX_SENSE0;
> +		hdmi->sink_detect_polarity = HDMI_PHY_RX_SENSE0;
> +		hdmi->sink_detect_mask = ~HDMI_PHY_RX_SENSE0;
> +	}
> +
>  	/*
>  	 * Configure registers related to HDMI interrupt
>  	 * generation before registering IRQ.
>  	 */
> -	hdmi_writeb(hdmi, HDMI_PHY_HPD, HDMI_PHY_POL0);
> +	hdmi_writeb(hdmi, hdmi->sink_detect_polarity, HDMI_PHY_POL0);
>  
>  	/* Clear Hotplug interrupts */
> -	hdmi_writeb(hdmi, HDMI_IH_PHY_STAT0_HPD, HDMI_IH_PHY_STAT0);
> +	hdmi_writeb(hdmi, hdmi->sink_detect_status, HDMI_IH_PHY_STAT0);
>  
>  	ret = imx_hdmi_fb_registered(hdmi);
>  	if (ret)
> @@ -1720,7 +1736,7 @@ static int imx_hdmi_bind(struct device *dev, struct device *master, void *data)
>  		goto err_iahb;
>  
>  	/* Unmute interrupts */
> -	hdmi_writeb(hdmi, ~HDMI_IH_PHY_STAT0_HPD, HDMI_IH_MUTE_PHY_STAT0);
> +	hdmi_writeb(hdmi, ~hdmi->sink_detect_status, HDMI_IH_MUTE_PHY_STAT0);
>  
>  	ret = snd_dw_hdmi_probe(&hdmi->audio, dev, hdmi->regs, irq, hdmi);
>  	if (ret)
> -- 
> 1.8.5.2
>