From: Tomi Valkeinen <tomi.valkeinen@ti.com>
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
Subject: Re: [PATCHv2 09/15] OMAP: DSS2: HDMI: implement detect()
Date: Wed, 14 Sep 2011 14:11:49 +0000 [thread overview]
Message-ID: <1316009509.2118.6.camel@deskari> (raw)
In-Reply-To: <CAP5A+B9Me0RX3PY7Uwf=VuaHzaPtoNY0q9gxFg9H-Q3N2giC2Q@mail.gmail.com>
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@ti.com> 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@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.
> >
> 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
next prev parent reply other threads:[~2011-09-14 14:11 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-12 9:13 [PATCHv2 00/15] OMAP: DSS2: EDID & detect support Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 01/15] OMAP: DSS2: add read_edid() to omap_dss_driver struct Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 02/15] OMAP: DSS2: add detect() " Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 03/15] OMAP: DSS2: HDMI: make set_timing saner Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 04/15] OMAP: DSS2: HDMI: implement read_edid() Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 05/15] OMAP: DSS2: HDMI: remove edid parsing Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 06/15] OMAP: DSS2: HDMI: split hdmi_core_ddc_edid Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 07/15] OMAP: DSS2: HDMI: clean up edid reading & fix checksum Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 08/15] OMAP: DSS2: HDMI: remove error prints in check_timings Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 09/15] OMAP: DSS2: HDMI: implement detect() Tomi Valkeinen
2011-09-12 13:36 ` K, Mythri P
2011-09-12 16:18 ` Tomi Valkeinen
2011-09-12 16:46 ` Rob Clark
2011-09-14 5:46 ` K, Mythri P
2011-09-14 7:14 ` Tomi Valkeinen
2011-09-14 8:39 ` K, Mythri P
2011-09-14 8:34 ` Tomi Valkeinen
2011-09-14 8:48 ` K, Mythri P
2011-09-14 8:57 ` Tomi Valkeinen
2011-09-14 12:32 ` K, Mythri P
2011-09-14 14:11 ` Tomi Valkeinen [this message]
2011-09-15 5:53 ` K, Mythri P
2011-09-15 5:57 ` Tomi Valkeinen
2011-09-15 6:36 ` K, Mythri P
2011-09-15 6:32 ` Tomi Valkeinen
2011-09-16 12:53 ` K, Mythri P
2011-09-19 6:50 ` Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 10/15] OMAP: DSS2: add panel-dvi driver Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 11/15] OMAP: use dvi panel driver instead of generic-dpi Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 12/15] OMAP: stalker: Remove LCD device from board file Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 13/15] OMAP: DSS2: panel-generic-dpi: remove "generic" panel Tomi Valkeinen
2011-09-12 9:13 ` [PATCHv2 14/15] OMAP: Panda, Beagle, Overo: DVI: Add i2c_bus_num Tomi Valkeinen
2011-09-12 9:58 ` Enric Balletbò i Serra
2011-09-12 10:17 ` [PATCHv2 14/15] OMAP: Panda, Beagle, Overo: DVI: Add Tomi Valkeinen
2011-09-12 11:13 ` [PATCHv2 14/15] OMAP: Panda, Beagle, Overo: DVI: Add i2c_bus_num Enric Balletbò i Serra
2011-09-12 9:13 ` [PATCHv2 15/15] OMAPFB: find best mode from edid Tomi Valkeinen
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