drm: bridge: dw_hdmi: only trigger hotplug event on link change

There are two events that signal a real change of the link state: HPD going
high means the sink is newly connected or wants the source to re-read the
EDID, RX sense going low is a indication that the link has been disconnected.

Ignore the other two events that also trigger interrupts, but don't need
immediate attention: HPD going low does not necessarily mean the link has
been lost and should not trigger a immediate read of the status. RX sense
going high also does not require a detect cycle, as HPD going high is the
right point in time to read the EDID.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com> (v1)
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220826185733.3213248-1-l.stach@pengutronix.de

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 25a60eb..40d8ca3 100644 (file)
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -3096,6 +3096,7 @@ static irqreturn_t dw_hdmi_irq(int irq, void *dev_id)
 {
        struct dw_hdmi *hdmi = dev_id;
        u8 intr_stat, phy_int_pol, phy_pol_mask, phy_stat;
+       enum drm_connector_status status = connector_status_unknown;
 
        intr_stat = hdmi_readb(hdmi, HDMI_IH_PHY_STAT0);
        phy_int_pol = hdmi_readb(hdmi, HDMI_PHY_POL0);
@@ -3134,13 +3135,15 @@ static irqreturn_t dw_hdmi_irq(int irq, void *dev_id)
                        cec_notifier_phys_addr_invalidate(hdmi->cec_notifier);
                        mutex_unlock(&hdmi->cec_notifier_mutex);
                }
-       }
 
-       if (intr_stat & HDMI_IH_PHY_STAT0_HPD) {
-               enum drm_connector_status status = phy_int_pol & HDMI_PHY_HPD
-                                                ? connector_status_connected
-                                                : connector_status_disconnected;
+               if (phy_stat & HDMI_PHY_HPD)
+                       status = connector_status_connected;
+
+               if (!(phy_stat & (HDMI_PHY_HPD | HDMI_PHY_RX_SENSE)))
+                       status = connector_status_disconnected;
+       }
 
+       if (status != connector_status_unknown) {
                dev_dbg(hdmi->dev, "EVENT=%s\n",
                        status == connector_status_connected ?
                        "plugin" : "plugout");