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'.

Signed-off-by: Philipp Zabel p.zabel@pengutronix.de --- This patch is updated from http://www.spinics.net/lists/linux-driver-devel/msg45207.html and rebased on top of Andy Yan's "dw-hdmi: convert imx hdmi to bridge/dw_hdmi" series. --- Documentation/devicetree/bindings/drm/imx/hdmi.txt | 2 ++ drivers/gpu/drm/bridge/dw_hdmi.c | 40 ++++++++++++++++------ 2 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/Documentation/devicetree/bindings/drm/imx/hdmi.txt b/Documentation/devicetree/bindings/drm/imx/hdmi.txt index 1b756cf..c997a3a 100644 --- a/Documentation/devicetree/bindings/drm/imx/hdmi.txt +++ b/Documentation/devicetree/bindings/drm/imx/hdmi.txt @@ -22,6 +22,8 @@ Required properties:

Optional properties: - ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing + - hpd-unreliable : if present, the HPD line is to be ignored and the driver + should instead use a workaround for sink detection.

example:

diff --git a/drivers/gpu/drm/bridge/dw_hdmi.c b/drivers/gpu/drm/bridge/dw_hdmi.c index cecc46a..b88225c 100644 --- a/drivers/gpu/drm/bridge/dw_hdmi.c +++ b/drivers/gpu/drm/bridge/dw_hdmi.c @@ -125,6 +125,9 @@ struct dw_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; @@ -1267,10 +1270,10 @@ static int dw_hdmi_fb_registered(struct dw_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; } @@ -1490,18 +1493,19 @@ static irqreturn_t dw_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);

dw_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);

dw_hdmi_poweroff(hdmi); } @@ -1509,7 +1513,7 @@ static irqreturn_t dw_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; } @@ -1648,6 +1652,16 @@ int dw_hdmi_bind(struct device *dev, struct device *master,

initialize_hdmi_ih_mutes(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; + } + /* * To prevent overflows in HDMI_IH_FC_STAT2, set the clk regenerator * N and cts values before enabling phy @@ -1658,10 +1672,14 @@ int dw_hdmi_bind(struct device *dev, struct device *master, * 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_IH_PHY_STAT0_RX_SENSE3 | HDMI_IH_PHY_STAT0_RX_SENSE2 | + HDMI_IH_PHY_STAT0_RX_SENSE1 | HDMI_IH_PHY_STAT0_RX_SENSE0 | + HDMI_IH_PHY_STAT0_TX_PHY_LOCK | HDMI_IH_PHY_STAT0_HPD, + HDMI_IH_PHY_STAT0);

ret = dw_hdmi_fb_registered(hdmi); if (ret) @@ -1672,7 +1690,7 @@ int dw_hdmi_bind(struct device *dev, struct device *master, 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);

dev_set_drvdata(dev, hdmi);