Hi, On Wed, Sep 14, 2011 at 7:41 PM, Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote: > 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 <tomi.valkeinen@xxxxxx> wrote: >> > 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@xxxxxx> 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@xxxxxx> 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. >> > >> 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. > If it is needed for DRM then it is fine, but with detect renamed to poll. By next week i should have a patch ready for HPD event mechanism. > Tomi > > > Thanks and regards, Mythri. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
