From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tomi Valkeinen <tomi.valkeinen@ti.com>
Subject: Re: [PATCHv2 09/15] OMAP: DSS2: HDMI: implement detect()
Date: Wed, 14 Sep 2011 11:57:10 +0300
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To: "K, Mythri P" <mythripk@ti.com>
Cc: Rob Clark <robdclark@gmail.com>, linux-omap@vger.kernel.org, linux-fbdev@vger.kernel.org, archit@ti.com

On Wed, 2011-09-14 at 14:18 +0530, K, Mythri P wrote:
> On Wed, Sep 14, 2011 at 2:04 PM, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
> > On Wed, 2011-09-14 at 13:57 +0530, K, Mythri P wrote:
> >> On Wed, Sep 14, 2011 at 12:44 PM, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:

<snip>

> > I don't understand this one. How could this be more dynamic? The
> > function checks the HPD bit, which (based on my observation) shows the
> > status whether a display is connected or not.
> There is a GPIO which detects the +3.3V on the line and detects the
> cable connect , there is also an interrupt based way.This is ideally
> called a Hot-plug detect event according to the spec in HDMI terms.
> But what you are saying here is that it is just a poll on the state?

Yes, it's just for polling, but I don't quite see the difference. A
hot-plug event notifies when the display is connected or disconnected,
and detect() tells if a display is connected. They are all about the
same thing.

> >> So I said if the purpose of this function is only to check for the HPD
> >> state bit it is fine.
> >
> > What does HPD bit tell us then?
> 
> HPD state bit tells whether the cable is connected and whether EDID is

This sounds like a good bit to test then. So is there something wrong
with using HPD? How does the GPIO differ from HPD bit?

> ready to be read, But this is a static check that is done in this
> function.

I don't understand what you mean with "static". The bit changes
dynamically according to the connect/disconnect state, and the bit is
checked dynamically when detect() is called.

 Tomi