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[PATCH] drm/bridge: dw-hdmi: fix hdmi display lost

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  [PATCH] drm/bridge: dw-hdmi: fix hdmi display lost Mark Yao <mark.yao@rock-chips.com> - 2016-08-11 10:00 +0200
    Re: [PATCH] drm/bridge: dw-hdmi: fix hdmi display lost Russell King - ARM Linux <linux@armlinux.org.uk> - 2016-08-11 10:40 +0200

#1460240 — [PATCH] drm/bridge: dw-hdmi: fix hdmi display lost

hdmi->disabled maybe not match to the real hardware status.

->dw_hdmi_bridge_enable()
  hdmi->disabled = false;
-->dw_hdmi_update_power()
   if (hdmi->rxsense)
       force = DRM_FORCE_ON;
   else
       force = DRM_FORCE_OFF;

hdmi->rxsense maybe false on bridge enable path, then hdmi->disabled
is false, but actually hardware is power off, they are not match.

So on dw_hdmi_irq, judge the hardware status with hdmi->disabled is wrong.
This bug would cause display lost, unplug/plug can't recovery display.

Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Liu Ying <gnuiyl@gmail.com>

Signed-off-by: Mark Yao <mark.yao@rock-chips.com>
---
 drivers/gpu/drm/bridge/dw-hdmi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
index 77ab473..a4fcb47 100644
--- a/drivers/gpu/drm/bridge/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/dw-hdmi.c
@@ -1563,7 +1563,7 @@ static irqreturn_t dw_hdmi_irq(int irq, void *dev_id)
 	if (intr_stat &
 	    (HDMI_IH_PHY_STAT0_RX_SENSE | HDMI_IH_PHY_STAT0_HPD)) {
 		mutex_lock(&hdmi->mutex);
-		if (!hdmi->disabled && !hdmi->force) {
+		if (!hdmi->bridge_is_on && !hdmi->force) {
 			/*
 			 * If the RX sense status indicates we're disconnected,
 			 * clear the software rxsense status.
-- 
1.9.1

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#1460262

On Thu, Aug 11, 2016 at 03:54:03PM +0800, Mark Yao wrote:
> hdmi->disabled maybe not match to the real hardware status.
> 
> ->dw_hdmi_bridge_enable()
>   hdmi->disabled = false;
> -->dw_hdmi_update_power()
>    if (hdmi->rxsense)
>        force = DRM_FORCE_ON;
>    else
>        force = DRM_FORCE_OFF;
> 
> hdmi->rxsense maybe false on bridge enable path, then hdmi->disabled
> is false, but actually hardware is power off, they are not match.

... which is correct.  If rxsense is false, it means there is nothing
plugged in, so we don't power the hardware up until something _is_
plugged in.

When something is plugged in, we get the HPD and RXSENSE events, which
will cause dw_hdmi_update_power() to be called.

hdmi->disabled is merely a bit mask of things that would cause us to
want to avoid powering the hardware up when rxsense becomes true.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

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