On Wed, 2011-09-14 at 17:50 +0530, K, Mythri P wrote:

Hi,

On Wed, Sep 14, 2011 at 2:27 PM, Tomi Valkeinen [off-list ref] wrote:

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On Wed, 2011-09-14 at 14:18 +0530, K, Mythri P wrote:

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On Wed, Sep 14, 2011 at 2:04 PM, Tomi Valkeinen [off-list ref] wrote:

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On Wed, 2011-09-14 at 13:57 +0530, K, Mythri P wrote:

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On Wed, Sep 14, 2011 at 12:44 PM, Tomi Valkeinen [off-list ref] wrote:

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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.

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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?

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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.

Well ! Who would call the detect and why ? By Dynamic i meant when the
cable is physically disconnected and connected there is detection
logic which can be implemented either by GPIo/Interrupts.
When you say the cable is connected , what happens in this case when
the cable is connected to say monitor of one resolution and then
plugged out and put to the other. Instead with dynamic method the
based on the physical connect and disconnect the notification would be
sent to any listener.

Ok, I see now what you mean.

Yes, you are right, detect() does not "know" if the monitor has changed
between polls, so both notification and polling are needed. I
implemented only polling as there's no HPD event mechanism yet in
omapdss, and also because this was simple and gives DRM basic ability to
detect a monitor.

 Tomi